tomahawk: Update to new upstream version 0.8.3.

Upstream changes since 0.8.2:

  * Performance improvements for collection browsing.
  * Improved memory footprint.
  * Show cloud collections above your friends in the sidebar.
  * Keep looking for alternative sources even when we found a perfect match.
  * Fixed crash in network code.
  * Fixed repeat one/all icons.
  * Be more lenient about accepting JSPF and M3U playlists.
  * Improved support for compilation albums.
  * (Windows) Fixed support for Windows XP.
  * (OS X) Fixed settings dialog appearance on Yosemite.
  * (OS X) Fixed SSL errors on Yosemite.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>