gst/rtp/: Add raw video pay and depayloaders, see RFC4175.

gst/rtp/: Add raw video pay and depayloaders, see RFC4175.

Original commit message from CVS:
* gst/rtp/Makefile.am:
* gst/rtp/gstrtp.c: (plugin_init):
* gst/rtp/gstrtpvrawdepay.c: (gst_rtp_vraw_depay_base_init),
(gst_rtp_vraw_depay_class_init), (gst_rtp_vraw_depay_init),
(gst_rtp_vraw_depay_setcaps), (gst_rtp_vraw_depay_process),
(gst_rtp_vraw_depay_change_state),
(gst_rtp_vraw_depay_plugin_init):
* gst/rtp/gstrtpvrawdepay.h:
* gst/rtp/gstrtpvrawpay.c: (gst_rtp_vraw_pay_get_type),
(gst_rtp_vraw_pay_base_init), (gst_rtp_vraw_pay_class_init),
(gst_rtp_vraw_pay_init), (gst_rtp_vraw_pay_finalize),
(gst_rtp_vraw_pay_setcaps), (gst_rtp_vraw_pay_handle_buffer),
(gst_rtp_vraw_pay_plugin_init):
* gst/rtp/gstrtpvrawpay.h:
Add raw video pay and depayloaders, see RFC4175.