Log tab added to download and remove logs
Moved Log tab to Settings
Fixed indentation
Removed unused parts from backend code, moved formatting to frontend, added date column, switched to modification date (might be more interesting in case of the log files)
Merge branch 'devel' into Salandora-logDownload
Added API documentation, adjusted API and returned data model slightly to be consistent with other parts of the API, made log file management restricted to admins.

TODO: Make downloading of logs also restricted to admins
Properly authenticate log file downloads on Tornado as well

Only allow for users with role admin.