RTGOV-439 Elasticsearch implementation of the SituationStore API. Refactored the ES activity store (and keyvaluestore) to move ES client capabilities into a separate class, primarily initiated because SituationStore is derived from another base class, and could therefore not derive from the ES keyvaluestore - so made it easier to extract out all ES capabilities. RTGOV-452 Fixed elasticsearch activity store to return full activity unit
RTGOV-466 Blank situatons, and array index exceptions, were due to situation store using the wrong type
Merge pull request #88 from objectiser/RTGOV-439

Rtgov 439