replace gst_element_class_set_details_simple with gst_element_class_set_metadata

opus: port to updated 0.11

Merge remote-tracking branch 'origin/master' into 0.11-premerge

Conflicts:
docs/libs/Makefile.am
ext/kate/gstkatetiger.c
ext/opus/gstopusdec.c
ext/xvid/gstxvidenc.c
gst-libs/gst/basecamerabinsrc/Makefile.am
gst-libs/gst/basecamerabinsrc/gstbasecamerasrc.c
gst-libs/gst/basecamerabinsrc/gstbasecamerasrc.h
gst-libs/gst/video/gstbasevideocodec.c
gst-libs/gst/video/gstbasevideocodec.h
gst-libs/gst/video/gstbasevideodecoder.c
gst-libs/gst/video/gstbasevideoencoder.c
gst/asfmux/gstasfmux.c
gst/audiovisualizers/gstwavescope.c
gst/camerabin2/gstcamerabin2.c
gst/debugutils/gstcompare.c
gst/frei0r/gstfrei0rmixer.c
gst/mpegpsmux/mpegpsmux.c
gst/mpegtsmux/mpegtsmux.c
gst/mxf/mxfmux.c
gst/videomeasure/gstvideomeasure_ssim.c
gst/videoparsers/gsth264parse.c
gst/videoparsers/gstmpeg4videoparse.c

opusenc: add upstream negotiation for multistream ability

This will help elements that cannot deal with multistream,
such as the RTP payloader.

The caps now do not include a "streams" field anymore, but
a "multistream" boolean, since we have no real use for knowing
the exact amount of streams.

https://bugzilla.gnome.org/show_bug.cgi?id=665078

Adding opus RTP payloader/depayloader element

Adding OPUS RTP module based on the current draft:
http://tools.ietf.org/id/draft-spittka-payload-rtp-opus-00.txt

https://bugzilla.gnome.org/show_bug.cgi?id=664817