media-manager: Fetch languages from Tracker

Fetch list of supported languages for each ISO file from Tracker.

https://bugzilla.gnome.org/show_bug.cgi?id=729122
Delete now redundant display-properties.vala file

https://bugzilla.gnome.org/show_bug.cgi?id=729258
Updated Belarusian translation.

(cherry picked from commit 514a68f5ad44a7a7032c9deb6df9d60042f8edce)