Upstream requested for gda-b rowser appdata

[ryanlerch]

We have requested upstream for gda-browser to include an appdata file. The upstream bug is:
https://bugzilla.gnome.org/show_bug.cgi?id=732868

[ryanlerch]

Added an appdata file here in the appstream for gda-browser, and contacted upstreamabout the appdata file.
https://github.com/hughsie/fedora-appstream/blob/master/appdata-extra/desktop/gda-browser-5.0.appdata.xml