ext/vorbis/vorbisdec.c (vorbis_handle_comment_packet): Post a message to the bus with the tags. Still not sent downst...

Original commit message from CVS:
* ext/vorbis/vorbisdec.c (vorbis_handle_comment_packet): Post a
message to the bus with the tags. Still not sent downstream tho.

* gst/playback/gstdecodebin.c (remove_element_chain): Unref after
get_parent.
(remove_element_chain): Use OBJECT_PARENT instead of get_parent to
avoid refcounting hassles.