make sure that the version app always work on the users real home folder

make sure that the version app always works on the users real home folder and not the mount point.

Fix for issue #1834 

I could only simulate the problem by forcing OC_User::getHome() to return a different home than data/uid. In this environment it looks like all issues mentioned in the bug report are solved with this patch. Still it would be great if someone who is also able to test it with a real LDAP setup could have a look at it... @blizzz ?