ext/jpeg/: Various cleanups, capsnego and leak fixes.

ext/jpeg/: Various cleanups, capsnego and leak fixes.

Original commit message from CVS:
* ext/jpeg/gstjpegenc.c: (gst_jpegenc_getcaps):
* ext/jpeg/gstsmokedec.c: (gst_smokedec_class_init),
(gst_smokedec_init), (gst_smokedec_finalize), (gst_smokedec_chain),
(gst_smokedec_change_state):
* ext/jpeg/gstsmokeenc.c: (gst_smokeenc_class_init),
(gst_smokeenc_init), (gst_smokeenc_finalize),
(gst_smokeenc_getcaps), (gst_smokeenc_setcaps),
(gst_smokeenc_resync), (gst_smokeenc_chain),
(gst_smokeenc_set_property), (gst_smokeenc_get_property),
(gst_smokeenc_change_state):
Various cleanups, capsnego and leak fixes.