gst-omx: fix version and RPi config

Use the rpi config from the official repository
gst-plugins-bad.bbappend: re-enable the default yocto plugins + videoparsers

The defult plugin set got accidentaly disabled when the id3tag plugin was
added.

Enable the videoparsers plugin, for things like h264parse.
userland.bbappend: fix up RPi userland package to install into /usr
gst-omx: changed the RPi runtime dependency to libopenmaxil
raspberrypi.conf: change libgles2/egl provider to userland
task-guacamayo-core: for RPi include gst-omx
task-guacamayo-core: only pull in gst-omx on RPi if DISTRO_FEATURES says so

The OpenMax functionality is broken in recent firmwares, which in turns
breaks thumbnailing in max, so we want this off by default.