Caches divided up into two groups: distributed and local. 'Low latency' is an
alias for local caches, while the standard `create()` call tries to get
distributed caches first, then local caches.

Memcache backend is set in `config.php`, with the keys `memcache.local` and
`memcache.distributed`. If not set, `memcache.distributed` defaults to the value
of `memcache.local`.

Doing this in the PHP code is not the right approach for multiple reasons:

1. A bug in the PHP code prevents them from being added to the response.
2. They are only added when something is served via PHP and not in other cases (that makes for example the newest IE UXSS which is not yet patched by Microsoft exploitable on ownCloud)
3. Some headers such as the Strict-Transport-Security might require custom modifications by administrators. This was not possible before and lead to buggy situations.

This pull request moves those headers out of the PHP code and adds a security check to the admin settings performed via JS.

use flock instead of just checking if there is a file to prevent deadlocks when the process crashed or the unlink wasnt done

move cron.lock into top directory to prevent external storage issues

use tmp directory lock file

use new config interface

incorporate #13770

add dots

This change allows AppFramework applications to specify a custom CSP header for example when the default policy is too strict. Furthermore this allows us to partially migrate away from CSS and allowed eval() in our JavaScript components.

Legacy ownCloud components will still use the previous policy. Application developers can use this as following in their controllers:
```php
$response = new TemplateResponse('activity', 'list', []);
$cspHelper = new ContentSecurityPolicyHelper();
$cspHelper->addAllowedScriptDomain('www.owncloud.org');
$response->addHeader('Content-Security-Policy', $cspHelper->getPolicy());
return $response;
```

Fixes https://github.com/owncloud/core/issues/11857 which is a pre-requisite for https://github.com/owncloud/core/issues/13458 and https://github.com/owncloud/core/issues/11925

Fixes https://github.com/owncloud/core/issues/13657

This allows the directory where CSS/JS asset collections are
written to be changed, in case SERVERROOT is not writeable. Note
it does *not* allow the expected URL to be changed: whatever
directory is used, the server must be configured to serve it
at WEBROOT/assets. It may be possible to add another config
parameter to allow the admin to specify a custom asset URL,
but I thought I'd keep the first implementation simple.

LDAP User Cleanup

background job for user clean up

adjust user backend for clean up

register background job

remove dead code

dependency injection

make Helper non-static for proper testing

check whether it is OK to run clean up job. Do not forget to pass arguments.

use correct method to get the config from server

methods can be private, proper indirect testing is given

no automatic user deletion

make limit readable for test purposes

make method less complex

add first tests

let preferences accept limit and offset for getUsersForValue

DI via constructor does not work for background jobs

after detecting, now we have retrieving deleted users and their details

we need this method to be public for now

finalize export method, add missing getter

clean up namespaces and get rid of unnecessary files

helper is not static anymore

cleanup according to scrutinizer

add cli tool to show deleted users

uses are necessary after recent namespace change

also remove user from mappings table on deletion

add occ command to delete users

fix use statement

improve output

big fixes / improvements

PHP doc

return true in userExists early for cleaning up deleted users

bump version

control state and interval with one config.php setting, now ldapUserCleanupInterval. 0 will disable it. enabled by default.

improve doc

rename cli method to be consistent with  others

introduce ldapUserCleanupInterval in sample config

don't show last login as unix epoche start when no  login happend

less log output

consistent namespace for OfflineUser

rename GarbageCollector to DeletedUsersIndex and move it to user subdir

fix unit tests

add tests for deleteUser

more test adjustements

Conflicts:
	apps/user_ldap/ajax/clearMappings.php
	apps/user_ldap/appinfo/app.php
	apps/user_ldap/lib/access.php
	apps/user_ldap/lib/helper.php
	apps/user_ldap/tests/helper.php
	core/register_command.php
	lib/private/preferences.php
	lib/private/user.php

add ldap:check-user to check user existance on the fly

Conflicts:
	apps/user_ldap/lib/helper.php

forgotten file

PHPdoc fixes, no code change

and don't forget to adjust tests

Hopefully this prevents people from using it in the future.

Workaround required for IIS setups running ownCloud to prevent dataloss.

Long-term solution would be to move some configuration settings to the database

This lead to a lot of confusion in the past and did not really offer any value. Let's remove the port check therefore. (it's anyways not really a part of the domain)

Fixes https://github.com/owncloud/core/issues/12150 and https://github.com/owncloud/core/issues/12123 and also a problem reported by @DeepDiver1975.

Conflicts:
	lib/private/request.php

Public interface for hashing which also works with legacy ownCloud hashes and supports updating the legacy hash via a passed reference.

Follow-up of https://github.com/owncloud/core/pull/10219#issuecomment-61624662
Requires https://github.com/owncloud/3rdparty/pull/136

Add switch to enforce SSL for subdomains

Add unit tests

Add test for boolean values

Camel-case

Fix ugly JS

Quickfix for https://github.com/owncloud/core/issues/11064

This commit will make the supported DBs for installation configurable within config.php. By default the following databases are tested: "sqlite", "mysql", "pgsql". The reason behind this is that there might be instances where we want to prevent SQLite to be used by mistake.

To test this play around with the new configuration parameter "supportedDatabases".

There is not much sense in having these files marked executable, we should avoid that.