Move primaryKey injection earlier so it can successfully find/merge duplicate objects within a response.
Merge branch 'primaryKeyInjectionBugfix' of https://github.com/jonbrooks/MMRecord into 2.0.0

Conflicts:
	Source/MMRecord/MMRecordProtoRecord.h
	Source/MMRecord/MMRecordProtoRecord.m
	Source/MMRecord/MMRecordResponse.m