Remove "suggested-action" style in Cancel Button.

Remove the style "suggested-action" in Cancel Button according
to the new mockups at:
https://wiki.gnome.org/GnomeOS/Design/Whiteboards/SelectionPattern

https://bugzilla.gnome.org/show_bug.cgi?id=706800
cached playlist total duration fix.
Merge pull request #179 from sumansai14/master

cached playlist total duration fix.
Updated Galician translations
Merge pull request #180 from shivanipoddariiith/master

Add more description to the No Music found view
Removed debug output from empty view
Updated Norwegian bokmål translation
Updated Galician translations
Updated Czech translation
Updated Czech translation
Updated Brazilian Portuguese translation
Updated Slovenian translation
[l10n] Updated Italian translation.
Tajik translation added
Updated Slovenian translation
Added Irish translation
Updated Irish translation
Updated Polish translation
view: don't discover URIs synchronously

Doing IO in the main loop is always a bad idea. But we don't need
to, because GStreamer can be made to do all the processing in a
background thread and only report the final result.

https://bugzilla.gnome.org/show_bug.cgi?id=706019
Make pep8 and pyflakes happy