Enhanced multiSelect

Add security section to admin settings to enable the HTTPS enforcement

Remove setContentTypeHeader()

Remove uneeded file 

`OC_JSON::success` and `OC_JSON::error` are calling
`OC_JSON::encodedPrint`, which already sets these headers. So this two
calls are uneeded duplicates.

logout.php is a legacy file, which isn't used anymore in the ownCloud
code.

Currently it only allows the admin to enable or disable the HTTPS
enforcement, but in the future it could be expanded to further options.

The HTTPS enforcement only allows the admin to enforce it, if he is
connected via HTTPS. (To prevent admins to enable it without a proper
SSL setup)

add more linebreaks, replace SQL LIMIT with param

webdav returns "503 Service Unavailable" in case the ownCloud server is ...

translate move and rename error messages

OC_Connector_Sabre_Client no longer needed

webdav returns "503 Service Unavailable" in case the ownCloud server is currently in maintenance mode.

Fix minor files annoyances

This means that OC_Connector_Sabre_Client is no longer needed

 refs https://github.com/owncloud/core/commit/ae54364d7c8baf5138d166855db6431190963886

Fixing wrong documentation. Fixes https://github.com/owncloud/core/issues/1110 

remove css not selector - incompatible with ie8

fix pattern for database names - #629

Conflicts:
	apps/files/js/files.js

Files: prevent people from renaming files to '.'

adding file name checks and notifications to isFileNameValid() for . and empty file name

Updater progress feedback