Fix MySqlLiveRackspaceTest

- brooklynProps.put should take string values, rather than
  a list.
AbstractController: use PORT_NUMBER_SENSOR config

- Previously, it hard-coded HTTP_PORT rather than using
  key specified in the configuration
Expose FixedListMachineProvisioningLocation.getInUse

- Useful for testing; and no harm exposing it as returns a copy
  so result can't be side-effected.
Adds testInheritedConfigAvailableDeepInHierarchy

- Was added while trying to track down bug @grkvlt was seeing,
  but this wasn't the cause! A useful test to have though.
Fix AtomicReference.setIfDifferent

- was using != instead of .equals for object equality
JmxFeed: decrease polling logging to trace
Merge pull request #718 from aledsage/fix/various-20130425

Fix/various 20130425