fixes #23
no need to unref main loop after g_main_loop_quit
refactoring around main loop stuffs
quit the server on failure audio/video input startup
giving a exit code to switch server quit and stop testing on a failure (fixes #21, fixes #28)
changed test case expected_compose_count
warn possible pipeline, bus leaks; make test-composite-mode 1 minute only, pass test-composite-mode