Let the media library parse any new file it finds

This prevents us from taking shortcuts with the file creation time, and
will prove itself helpfull when we need even more informations about
file

This is mostly aiming at allowing us to fiddle with the mock FS during
tests.

Processing is done by a threadpool (limited to a single thread so far)
This will allow using asynchronous modules one after another
Fixing VLC service cleaup code

Rename name -> title

This will avoid random crash due to dangling pointer in case the DB was
released