Add tests for Sabre Auth plugin + make getCurrentUser compatible

Bump 3rdparty for phpseclib-2.0.0

Remove dead code from autoloader

Ensure the password is only hashed in case it's changed on the client…

Use optimized autoloader for files_external

Those variables are never written to. Thus this is dead code which should be removed.

Add HackerOne page to CONTRIBUTING.md

Use optimized autoloader for 3rdparty

Throw exception on `getPath` if file does not exist

Currently the `getPath` methods returned `NULL` in case when a file with the specified ID does not exist. This however mandates that developers are checking for the `NULL` case and if they do not the door for bugs with all kind of impact is widely opened.

This is especially harmful if used in context with Views where the final result is limited based on the result of `getPath`, if `getPath` returns `NULL` PHP type juggles this to an empty string resulting in all possible kind of bugs.

While one could argue that this is a misusage of the API the fact is that it is very often misused and an exception will trigger an immediate stop of execution as well as log this behaviour and show a pretty error page.

I also adjusted some usages where I believe that we need to catch these errors, in most cases this is though simply an error that should hard-fail.

Bump 3rdparty for guzzlehttp/http to 5.3.0

Includes bump of react/promise to 2.2.1

Dont lock /$user/files

Bump 3rdparty to have full sabre/dav-2.1.7

Provisioning api integration tests added app tests and getusers by a subadmin

Expose syslog tag in the configuration

Fix "Call to a member function getUID() on boolean" in Crypt

change wording from 'remember' to more understandable 'Stay logged in'

Even more code mess :(
All tests pass again. But I'm really not happy with this endpoint.

handle NoUserException in sharing code

Bump 3rdparty for pear/archive_tar-1.4.1

* setup LDAP users
* share from an LDAP user
* delete that LDAP user
* log in as share recipient
* before: unhandled NoUserException
* after: NoUserEception is logged and share is not shown anymore