Celery event monitor for agent

[lukasjuhrich]

We should provide the celery event monitor for the agent to be able to quickly debug whether RPC messages get through properly.

The following is a snippet that should provide an adequate wrapper around celery.events.cursesmon.

from celery.events.cursesmon import evtop

from hades.config import load_config
from hades.agent import create_app


app = create_app(load_config())
app.control.broadcast("enable_events")
try:
    evtop(app)
finally:
    app.control.broadcast("disable_events")

[lukasjuhrich]

(Snippet created to aid with #119)