Add update method to FabricJaasRealm.
Add onFailed callback to "wait for provisioning" operations, so that we can gather as much information as possible about the failure. Misc test improvements.

Conflicts:
	tooling/testing/pax-exam-karaf/src/main/java/org/fusesource/tooling/testing/pax/exam/karaf/FuseTestSupport.java