Mopidy / Spotify package?

[Trinket]

I recently did what you are trying now.
In order to install gstreamer you need to have the correct libtag version, I found out that another person had the same problem and it got solved in https://github.com/xbianonpi/xbian/issues/378 by installing another libtag version.
This bit is the one that did it for me, but read all the other information first!

Terminal

cd /tmp
wget http://ivka57.dyndns-ip.com/others/libtag1c2a1.7.2-1.deb
wget http://ivka57.dyndns-ip.com/pool/main/x/xbian-package-libtag/xbian-package-libtag_1.0-2_armhf.deb
dpkg -i *.deb

Once done, you will be able to install gstreamer and then mopidy without problems.