simplify set_view_filter: don't re-read media's artist and album

https://bugzilla.gnome.org/show_bug.cgi?id=726721
pep8: fix 'E713 test for membership should be 'not in'' and blacklist E265
pep8: remove unused _ imports
mrpis: don't crash if some field cannot be found
mpris: don't crash if some field is missing and check other options if possible

https://bugzilla.gnome.org/show_bug.cgi?id=726721
potfiles: add mpris.py
mpris: skip all the exception when fetching track info

https://bugzilla.gnome.org/show_bug.cgi?id=726721
query: Use double quotes for url in get_song_with_url

Single quotes are not escaped in URIs, which causes syntax errors in the query if
the URI has single quotes. Use double quotes instead.
player: mpris: skip all the exception when getting artist
Updated Hungarian translation
Updated French translation
Updated Slovenian translation
[l10n] Update Catalan translation
Remove old GIO-based file tracking method
Implement a simple logging for the application
Use a logger for all modules
Trap OSTree errors when adding sources

https://bugzilla.gnome.org/show_bug.cgi?id=727444
view: Show new playlist when current playlist is deleted

https://bugzilla.gnome.org/show_bug.cgi?id=724627
view: Show first playlist on populate if available
view: Show newly created playlist if it's the only playlist