Adds Transformer enricher transformatoinFromEvent

- instead of just transforming sensor value, can supply a function
  for SensorEvent -> val (e.g. if need to look up source entity etc)
Fix BrooklynAccessUtils for entities with multiple locs

- some entities have the provisioning-location and them machine-location
  added to them. So need to find the one SupportsPortForwarding,
  rather than assuming there will be exactly one location
Adds LoadBalancer.HOST_AND_PORT_SENSOR

- For a single sensor that gives host:port
  This is particularly useful when transforming sensor values,
  e.g. in port-mappings, where we want to convert a port the the
  host:port that it can be accessed on.
Fix time-sensitive AbstractGeoDnsServiceTest
Improve err messages in EntityTestUtils
Make DynamicMultiGroup extend DynamicGroup
Add configurable rescan interval
Tidy up dynamic groups and fix implementation of distributeEntities
Further tidying and cleanup of formatting
Merge pull request #1265 from aledsage/fix/docker

Fixes for docker testing
Small changes to Javadoc
Merge pull request #1260 from grkvlt/enhancement/dynamic-multi-group-group

Make DynamicMultiGroup extend DynamicGroup