Add simple exmple app to demonstrate starting and pausing live and non-live bins in a PLAYING pipeline.

Original commit message from CVS:
* configure.ac:
* tests/examples/Makefile.am:
* tests/examples/dynamic/.cvsignore:
* tests/examples/dynamic/Makefile.am:
* tests/examples/dynamic/addstream.c: (create_stream),
(pause_play_stream), (message_received), (eos_message_received),
(perform_step), (main):
Add simple exmple app to demonstrate starting and pausing live and
non-live bins in a PLAYING pipeline.