DynamicFabric: implement group

- So that summingEnricher, etc can automatically pick up members.
- So has symmetry with DynamicCluster.
Adds DynamicWebAppFabric
Adds DynamicFabric.getFabricSize()
Application builder: for raw-classes, proxy implements all interfaces

- If creating an application (passing in impl Class), then want
  proxy to implement all of its interfaces.
- Adds EntitySpec.getAdditionalInterfaces
- Adds minor conveniences to MutableList.builder and MutableSet.builder
- BrooklynRestResourceUtils.create() looks up additional interfaces
- Fix wrong import on REST's ApplicationSpec
- Fix REST's ApplicationSpec.type for inner classes:
  use type.getName() instead of getCanonicalName() so can be
  subsequently classloaded.
Entities.dumpInfo(entity) includes policy conf
AutoScalerPolicy.reconfigure min/max pool size

- Resize immediately if current size is outside of the new min/max
  pool size bounds.
- Creates AutoScalerPolicyReconfiguratoinTest, moving tests out of
  AutoScalerPolicyMetricTest.
DynamicWebAppCluster.SERVICE_UP only if member up

- Tracks members (added/removed/serviceUp) to set cluster's serviceUp
  to true if at least one member is up, and to false otherwise.
Merge pull request #550 from aledsage/feature/DynamicWebAppFabric

Adds dynamic web app fabric