Log tab added to download and remove logs
added basic terminal command history

use up/down keys to navigate through command history.
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
minor cleanup on command history.  removing unneeded var.
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.
Merge branch 'devel' into chriskoz-terminalHistorySupport
Slight refactoring of a PR

Corrected indentation, removed jumpy cursor, fixed off-by-one errors on history limits, limited history to a maximum of 300 entries ("300 items of command history should really be enough for anybody!")