Add people equivalence
If no people are resolved, return 404 rather than internal server error
Maintain person lookup entry store when saving people
don't attempt people merge with no precedence
Merge branch 'mbst-4778-people-equivalence' into stage

* mbst-4778-people-equivalence:
  don't attempt people merge with no precedence
  Maintain person lookup entry store when saving people
  If no people are resolved, return 404 rather than internal server error
  Add people equivalence

Conflicts:
	src/main/java/org/atlasapi/persistence/MongoContentPersistenceModule.java
	src/main/java/org/atlasapi/persistence/content/mongo/MongoPersonStore.java
	src/main/java/org/atlasapi/persistence/content/people/EquivalatingPeopleResolver.java
	src/test/java/org/atlasapi/persistence/content/mongo/MongoPersonStoreTest.java