Update share.php

Added empty for error:
```
Undefined index: file_target at /var/www/owncloud/lib/private/share/share.php#1911
```
- Added test to trigger index id error
- re-enable encryption migration tests
- sqlite requires reconnect after schema changes

Backport of 10a2955 from master
Update info.xml
backport of #9628

Userlist: async load doesnt fill checked group/subadmin array

Strinct comparsion fix
use fileinfo object in search results
return relative path
mkae getRelativePath of file search results overwriteable in subclasses
fix logger implementation and test