Conflicts:
	apps/files_versions/templates/settings-personal.php

Update CONTRIBUTING.md

Thanks @eMerzh, could be especially needed as there are some platform specific issues like filename encoding under MS Windows

:oops:

Makes it at least better readable for me.

Move openid.php to apps repo

Conflicts:
	settings/routes.php

Add contribution file

- some more code comments
- fixed bug in the expire function, cleanup all_versions array during run. Otherwise it could happen that we try to delete already deleted versions

Enhanced multiSelect

Add security section to admin settings to enable the HTTPS enforcement

Remove setContentTypeHeader()

Remove uneeded file 

This belongs to the apps repo.

`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.