Getting oldest event from a bucket
A mixin for functions returning deferreds
Scheduler health check implemented

It is unhealthy if it is not allocted and when an event in any of the
buckets is too old
Merge branch 'master' into auto-862-scheduler-health

Conflicts:
	otter/test/test_scheduler.py
mock implements get_oldest_event
s/allocated/acquired - thanks a ton @cyli

This fixes health check and checking allocation when stopping service
typo fix
updated test for typo fix
Giving buckets allocated in health check
correct consistency level - thanks @cyli
1 minute scheduler threshold

Scheduler runs every 10 seconds and should be able to handle hundreds of
events in each run. I think 1 minute itself is too late for any event to
be there
scheduler health dict to json fix

version and trigger stored in old_events is not json serializable. Hence
replacing with their string version
Merge pull request #517 from rackerlabs/auto-862-scheduler-health

Auto 862 scheduler health check