gracefully handle helper method calls to objects that are not beeing controlled, added test case for that

Original commit message from CVS:
* check/gst-libs/controller.c: (GST_START_TEST),
(gst_controller_suite):
* docs/gst/tmpl/gstcaps.sgml:
* docs/gst/tmpl/gstghostpad.sgml:
* docs/gst/tmpl/gstquery.sgml:
* docs/gst/tmpl/gstutils.sgml:
* libs/gst/controller/gst-helper.c: (gst_object_set_controller),
(gst_object_sink_values), (gst_object_get_value_arrays),
(gst_object_get_value_array):
gracefully handle helper method calls to objects that are not beeing
controlled, added test case for that