Adds performance tests for BlobStore-backed persistence
Use thread pool for Object Store persistence

- passes BrooklynProperties to BrooklynMementoPersisterToObjectStore
  so can read config like max thread pool size.
Merge remote-tracking branch 'aledsage/test/Persist-to-ObjectStore' into more-persist-with-multiple-threads

Conflicts:
	core/src/main/java/brooklyn/entity/rebind/RebindExceptionHandlerImpl.java
	core/src/main/java/brooklyn/entity/rebind/persister/BrooklynMementoPersisterToObjectStore.java
	core/src/test/java/brooklyn/entity/rebind/RebindTestUtils.java
	core/src/test/java/brooklyn/management/ha/HighAvailabilityManagerSplitBrainTest.java
	core/src/test/java/brooklyn/management/ha/HighAvailabilityManagerTestFixture.java

    Merge conflicts due to exception handlers and enricher support added in #34 and #35.
    I think they have been resolved correctly.