Raise no exception for cfn-hup _is_valid_metadata()
Raise no exception for cfn-hup _is_valid_metadata()

Now info is logged that no AWS::CloudFormation::Init
existed in the metadata.
Fixes: bug #1155999

Change-Id: Ice7016c65a5bf18f50c3552629f7a182d48db1f2

bbandaru/heat-cfntools,openstack/heat-cfntools,steveb/heat-cfntools,steveb/heat-cfntools