Bump version to 3.9.90
Update README
Updated Polish translation
Updated Galician translations
Fixes for license notices

There are some missing words from the license notices, so added them in.
The non-GPL compatible GStreamer plugins exception is also added to the
license notices. Changed "Music" to "GNOME Music" in the license shown in
the About box.

https://bugzilla.gnome.org/show_bug.cgi?id=706457
Fix the upstream URL in the "about" dialog

This in fact fixes the URL in the configure.ac file, and then reuses
that in the "about" dialog.

If it needs to change in the future, then it can be changed only in one
place.

https://bugzilla.gnome.org/show_bug.cgi?id=706353
Ignore the generated headerbar.ui file
Fix formatting in About dialog

- Add a newline after the Contributors list to separate it with the
  Designers list
- List designers alphabetically
- Remove newlines in the license
- Enable wrapping of license

https://bugzilla.gnome.org/show_bug.cgi?id=706353
reset the duration before updating the album widget.
Updated Czech translation
Mark a string as translatable
Merge pull request #178 from sumansai14/master

Reset the duration before updating the album widget
Updated Brazilian Portuguese translation
Updated slovak translation
[l10n] Updated Italian translation.
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.
Add more description to the No Music found view
Editing set_label arguments