hub: mimic raise_error=false behaviour more correctly
hub: implement event.clear for topology/switches
hub: fix event
hub: print trace for uncaught exceptions
hub: some tests
hub: tests
hub: more tets
hub: more tests
hub: pep8 for tests
hub: tests
ovs.poller: workaround a bug in eventlet
vsctl test code from yamahata
ovs_vsctl.py: rebase and tweaks
ovs_vsctl.py: print timing info
add a ryuapp to provide python interactive console for debugging