Update to 1.6.1

Changelog:
This is GStreamer 1.6.1

The GStreamer team is proud to announce the first bugfix release in the stable
1.6 release series of your favourite cross-platform multimedia framework!

This release only contains bugfixes and it is safe to update from 1.6.0. For a
full list of bugfixes see Bugzilla:
  https://bugzilla.gnome.org/buglist.cgi?bug_status=RESOLVED&bug_status=VERIFIED&limit=0&list_id=73005&order=bug_id&product=GStreamer&resolution=FIXED&target_milestone=1.6.1

See http://gstreamer.freedesktop.org/releases/1.6/ for the latest version of this document.

Major bugfixes

- Crashes in the gst-libav encoders were fixed
- More DASH-IF test streams are working now
- Live DASH, HLS and MS SmoothStreaming streams work more reliable and other
  fixes for the adaptive streaming protocols
- Reverse playback works with scaletempo to keep the audio pitch
- Correct stream-time is reported for negative applied_rate
- SRTP packet validation during decoding does not reject valid packets anymore
- Fixes for audioaggregator and aggregator to start producing output at the
  right time, and e.g. not outputting lots of silence in the beginning
- gst-libav's internal ffmpeg snapshot was updated to 2.8.1
- cerbero has support for Mac OS X 10.11 (El Capitan)
- Various memory leaks were fixed, including major leaks in playbin, playsink
  and decodebin
- Various GObject-Introspection annotation fixes for bindings
- and many, many more: https://bugzilla.gnome.org/buglist.cgi?bug_status=RESOLVED&bug_status=VERIFIED&limit=0&list_id=73005&order=bug_id&product=GStreamer&resolution=FIXED&target_milestone=1.6.1

(ryoon)