use gstreamer 1.0 video/x-raw caps string
Implement setCaps as a CapsEvent.

test if we are a source or sink event and use the right event
send call.

use get_current_caps in the Pad::caps() call
parent-set signal was removed. Come up with some alternatives.
Caps don't seem to stick to pads unless its in StatePlaying

While figuring this out I added tests for for the most basic of steps.

I'm also not sure what happens if a test fails while it is in
playing, since that seems to start up another thread. (The tests might
not exit)