gst/: Leak fixes, the fold functions need to unref the passed object and _get_parent_*() returns ref to parent.

Original commit message from CVS:
* gst/elements/gsttee.c: (gst_tee_init), (gst_tee_do_push):
* gst/gstutils.c: (intersect_caps_func), (gst_pad_proxy_getcaps),
(link_fold_func), (gst_pad_proxy_setcaps):
Leak fixes, the fold functions need to unref the passed object and
_get_parent_*() returns ref to parent.