Initial implementation of Entity Connection (aka Graph Edge queries) in Core Persistence Query Index module.

https://issues.apache.org/jira/browse/USERGRID-121
Refactoring to arrive at one nice EntityIndex interface instead of two awkward ones.
Merge branch 'two-dot-o' into optimistic-tx-semantics

Conflicts:
	stack/corepersistence/queryindex/src/main/java/org/apache/usergrid/persistence/index/legacy/EntityManagerFacade.java