Bugfix: describe_event_bus()['Policy'] should be JSON string, not object
Bugfix: describe_event_bus()['Policy'] should be JSON string, not object


boto3.client('events')['Policy'] must be a string as per:
http://boto3.readthedocs.io/en/latest/reference/services/events.html#CloudWatchEvents.Client.describe_event_bus

Adding json.dumps() around the policy value ensures we do not return an unexpected dict

This change corrects an error when attempting to decode the policy:

json.load(boto3.client('events').describe_event_bus()['Policy'])
Brett55/moto,whummer/moto,whummer/moto,spulec/moto,botify-labs/moto,okomestudio/moto,Brett55/moto,spulec/moto,rocky4570/moto,botify-labs/moto,william-richard/moto,rocky4570/moto,Brett55/moto,rocky4570/moto,okomestudio/moto,whummer/moto,whummer/moto,rocky4570/moto,william-richard/moto,whummer/moto,spulec/moto,okomestudio/moto,william-richard/moto,william-richard/moto,botify-labs/moto,okomestudio/moto,botify-labs/moto,Brett55/moto,william-richard/moto,okomestudio/moto,okomestudio/moto,rocky4570/moto,botify-labs/moto,whummer/moto,spulec/moto,rocky4570/moto,spulec/moto,Brett55/moto,spulec/moto,Brett55/moto,william-richard/moto,botify-labs/moto