* Bring social icons to core

* Introduce social sharing

* Add missing mail-grey.svg

* Add config option to disable social sharing

* Smaller icons

* Twitter: set shared link as url in twitter field

* Fix tooltip to disappear on click

* Use DI to load console commands from the apps - class name to be defined in the info.xml

* Load commands from info.xml

* Fix unit test

* Allow Di magic for IMountManager

"Storage not available" is now "Storage temporarily not available".
Exceptions are now logged in DEBUG level, not FATAL.

Removes the need for POST to collection which would hit against upload
limits.

The client tries to auto rename the file by adding a suffix "(2)".
It tries to use the file list on the client side to guess a
suitable name. In case a file still cannot be uploaded and creates a
conflict, which can happen when the file was concurrently uploaded, the
logic will continue increasing the suffix.

Properly trigger the "stop" even from the uploader.
Also update storage stats at the end of all uploads instead of for each
upload.

The web UI now uses for PUT uploads which aren't restricted by PHP's
upload_max_filesize and post_max_size

Enhanced the REPORT method on the Webdav endpoint and added a
"oc:favorite" filter rule. When set, it will return a flat list of
results filtered with only favorite files.

The web UI was also adjusted to use this REPORT method instead of the
private API endpoint.

* Update phpunit dependency to 5.5

* getMock() -> createMock() or getMockBuilder()

* Fix integration tests - comment enable/disable app tests for now

* Update .htaccess

Hacked around Blueimp's jquery.fileupload to make it work with our new
chunking API.

- uses PUT method with jquery.fileupload for regular and public file
  lists
- for IE and browsers that don't support it, use POST with iframe
  transport
- implemented Sabre plugin to handle iframe transport and redirect the
  embedded PUT request to the proper handler
- added RFC5995 POST to file collection with "add-member" property to
  make it possible to auto-rename conflicting file names
- remove obsolete ajax/upload.php and obsolete ajax routes

Initialize files config with defaults in case none was passed