examples/: Removed gst123 and vorbisplay examples which weren't working with 0.10, and replaced them with decodebin.py

Original commit message from CVS:
reviewed by: Edward Hervey  <edward@fluendo.com>
* examples/decodebin.py:
* examples/gst123:
* examples/vorbisplay.py:
Removed gst123 and vorbisplay examples which weren't working with
0.10, and replaced them with decodebin.py
Closes #362183 and #362202