gst/parse/parse.l: Commit patch for parse_launch syntax from #331255. Removes support for quoted strings and mimetype...

Original commit message from CVS:
* gst/parse/parse.l:
Commit patch for parse_launch syntax from #331255. Removes
support for quoted strings and mimetypes when writing filtered
caps. See the bug report for more details - I'm pretty sure this
obscure feature is not in use by _anyone_ anywhere.

With this simple change, the size of the gstreamer.so here
drops from 2193KB to 1565KB.