[Merge] lp:~alfonsosanchezbeato/media-hub/fix-refs into lp:media-hub/stable

[Simon Fels]

Tested with silo 28 on arale. No leaking file descriptors anymore.

Used test script:

 $ while true ; do ls -1 /proc/`pidof media-hub-server`/fd | wc -l ; sleep 1 ; done

While playing different media files with video player and music-app.
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https://code.launchpad.net/~alfonsosanchezbeato/media-hub/fix-refs/+merge/273229
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