This changeset allows ownCloud to run with pretty URLs, they will be used if mod_rewrite and mod_env are available. This means basically that the `index.php` in the URL is not shown to the user anymore.

Also the not deprecated functions to generate URLs have been modified to support this behaviour, old functions such as `filePath` will still behave as before for compatibility reasons.

Examples:
http://localhost/owncloud/index.php/s/AIDyKbxiRZWAAjP => http://localhost/owncloud/s/AIDyKbxiRZWAAjP
http://localhost/owncloud/index.php/apps/files/ => http://localhost/owncloud/apps/files/

Due to the way our CSS and JS is structured the .htaccess uses some hacks for the final result but could be worse... And I was just annoyed by all that users crying for the removal of `index.php` ;-)

For enhanced security it is recommended to configure Redis to only accept connections with a password. (http://redis.io/topics/security)

This is especially critical since Redis supports the LUA scripting language and thus a simple SSRF vulnerability (as proven in http://benmmurphy.github.io/blog/2015/06/04/redis-eval-lua-sandbox-escape/ for example) may lead to a remote code execution.

This reverts commit 7cbdd9b9.

* if you install owncloud via package it is not
  possible to skip migration tests
* this also allows to disable migration tests for
  an instance by default

* ref #16891

that I noticed while looking at some code.

* introduces config.php option 'debug' that defaults to false
* migrate DEBUG constant to config value

This will prevent detecting remote changes done in the data folder /
root storage by default. In the rare cases where the data folder is
shared with other apps/users outside ownCloud and change detection is
needed, the admin will have to set the option explicitly from now on.

Note that this doesn't affect external storages which have their own
setting in the mount options.

Since we both use dir and httpd/unix-directory in OC they should map to
the same icon.

Fixes #17527

This allows users to create their own mapping file to extend our current
mappings. This makes sure that custom mappings are not lost on OC
upgrades.

This allows users to add new mimetypemappings (extention -> mimetype)
themself. And not have to wait until a new release for updated
mimetypes.

Fixes: #15384

This makes it possible to retrieve the icon for mimetypes in javascript.
It makes no additional queries to the server to retrieve the mimetype.

* config/mimetypealiases.json added
* mimetype.js: this is where the logic resides to convert from mimetype
  to icon url
* mimetypelist.js: generated file with a list of mimetype mapping (aliases)
  and the list of icon files
* ./occ maintenance:mimetypesjs : new command for occ to gernerate
  mimetypes.js
* unit tests updated and still work
* javascript tests added
* theming support
* folder of the theme is now present in javascript (OC.theme.folder)