gst/udp/: Ported udp src/sink.

gst/udp/: Ported udp src/sink.

Original commit message from CVS:
* gst/udp/Makefile.am:
* gst/udp/gstudpsink.c: (gst_udpsink_get_type),
(gst_udpsink_base_init), (gst_udpsink_class_init),
(gst_udpsink_init), (gst_udpsink_get_times), (gst_udpsink_render),
(gst_udpsink_set_property), (gst_udpsink_get_property),
(gst_udpsink_init_send), (gst_udpsink_close),
(gst_udpsink_change_state):
* gst/udp/gstudpsink.h:
* gst/udp/gstudpsrc.c: (gst_udpsrc_base_init),
(gst_udpsrc_class_init), (gst_udpsrc_init), (gst_udpsrc_loop),
(gst_udpsrc_set_property), (gst_udpsrc_get_property),
(gst_udpsrc_init_receive), (gst_udpsrc_close),
(gst_udpsrc_activate), (gst_udpsrc_change_state):
* gst/udp/gstudpsrc.h:
Ported udp src/sink.