feat(rest) added process instance suspension state
Merge branch 'act_susp_prcs_fix'

Conflicts:
	engine-rest/src/main/java/org/camunda/bpm/engine/rest/ProcessInstanceRestService.java
	engine-rest/src/main/java/org/camunda/bpm/engine/rest/impl/ProcessInstanceRestServiceImpl.java
	engine-rest/src/test/java/org/camunda/bpm/engine/rest/AbstractProcessInstanceRestServiceInteractionTest.java