Wrong integration test hides a flaw in Alerting

A bug introduced in an integration test:
https://github.com/hawkular/hawkular-services/blob/master/itest/src/test/java/org/hawkular/services/rest/test/MetricsAlertingITest.java#L135

hid a bug in Hawkular Alerting, where data was not properly prefixed once is back in the bus.

So, we need to fix the bug in hawkular alerting and fix this integration test.