Adds index population job and completor
An idea of index population->online handover
Introduces the new indexing cake and the index cake flip
Killed a race by turning AtomicDelegatingIC into RWLock-based FlippableIC
New schema indexes are now hooked in, such that creating an index will actually populate and eventually bring an index online

o Removed index state from IndexRule
Support for restarts and recovery on indexes, moves IndexingService creation into Xa
Implemented a SchemaIndexProvider for Lucene with support for the IndexPopulator
Adds property updates when labels are added/removed and more tests
Merged in changes from SP/JH commit

o Added WriteTransactionTest
Spotting TestIdReuse-related bug PropPhysToLogConv L 86
Merge remote-tracking branch 'plantikow/index-existing-data' into 2.0