This will help not to accidentially push private data and enable testing on our ci server.

Fixes #3466 because the test method of external filesystems uses stat() to detect if the given parameters are okay.

Changes to 3rdparty are necessary as well:
https://github.com/owncloud/3rdparty/pull/33

added our own file extension .part will not work here if we use file_get_contents so we used our own extension '.etmp'

prevent files_versions from calling file proxy which calls files_encryption and do unnecessary load and file operations

LDAP: fix generation of alternate internal name on conflicts. Use also smaller number for better user experience on e.g. *DAV links

fixed problems with file_get_contents and file_put_contents this problem was related to text editor with big text files

check list of users with access to the file from the bottom to the top. This way we avoid calling getFileInfo() on every dir, which creates a lot of overhead, especially for external storages