gst/rtp/: Add JPEG payloader. Fixes #560756.

gst/rtp/: Add JPEG payloader. Fixes #560756.

Original commit message from CVS:
Patch by: Bjorn Ostby <bjornos at axis dot com>
* gst/rtp/Makefile.am:
* gst/rtp/gstrtp.c: (plugin_init):
* gst/rtp/gstrtpjpegpay.c: (gst_rtp_jpeg_pay_base_init),
(gst_rtp_jpeg_pay_class_init), (gst_rtp_jpeg_pay_init),
(gst_rtp_jpeg_pay_setcaps), (gst_rtp_jpeg_pay_header_size),
(gst_rtp_jpeg_pay_read_quant_table),
(gst_rtp_jpeg_pay_scan_marker), (gst_rtp_jpeg_pay_handle_buffer),
(gst_rtp_jpeg_pay_set_property), (gst_rtp_jpeg_pay_get_property),
(gst_rtp_jpeg_pay_plugin_init):
* gst/rtp/gstrtpjpegpay.h:
Add JPEG payloader. Fixes #560756.