fix(rest) added additional history service tests

Conflicts:
	engine-rest/src/main/java/org/camunda/bpm/engine/rest/dto/history/HistoricActivityInstanceDto.java
	engine-rest/src/main/java/org/camunda/bpm/engine/rest/dto/history/HistoricProcessInstanceDto.java
	engine-rest/src/test/java/org/camunda/bpm/engine/rest/helper/MockProvider.java