CLOUDIFY-1944 riemann events module for sending riemann events from celery tasks.
Merge remote-tracking branch 'origin/feature/CLOUDIFY-1944-relationships' into feature/CLOUDIFY-1944-relationships
CLOUDIFY-1944 send riemann event in relevant plugins indicating nodes are running
CLOUDIFY-1944 return false on false plugin verification and use loop instead of on_error for repeating verification. pip install bernhard for celery worker.