Raise a new timeout error with useful info, instead of logging a msg and then CanceledError (with no further info) separately
Convert CancelledError to TimedOutError in timeout_deferred
retry_deferred also accepts a description
Change wait_for_active and verified_delete to just log the TimedOutError
logging scheduler policy exec failure with ids

when policy execution fails due BusyLockError or any other reason, the error is logged with tenant_id,
group_id and policy_id. Moved the collection of deleted policy ids to execute_event for this
Do not use a separate class to store a single variable, as per @dreid's suggestion
Refactor some test harnessing
AUTO-513: logging utcnow in ISO8601 format

Implemented utcisoformat() in utils/timestamp.py that gives ISO format of given time.
Also, improved the scheduler log bind test by mocking datetime and generate_transaction_id
Log formatter accomodates datetime and Failure objects

it converts datetime and failure objects into more readable format.
- Removed utcisoformat() function as we really dont know if a datetime is UTC.
- Reverted scheduler changes made by earlier commit
list of tuples instead of dict

since we are iterating anyways
pep8 fix
doc change and minor cleanup
more descriptive log
Merge branch 'master' into auto-488-better-timeout-logging

Conflicts:
	otter/worker/launch_server_v1.py
Better storage of timed-out state, as per @dreid's suggestions
Change the default timeout for verified delete
Merge pull request #343 from rackerlabs/auto-488-better-timeout-logging

Remove useless CancelledError logging
Merge pull request #346 from rackerlabs/auto-513-datetime-log

AUTO-513: logging utcnow in ISO8601 format
Merge pull request #344 from rackerlabs/scheduler_exec_err_log

logging scheduler policy exec failure with ids
Merge branch 'master' into bobby-tests