Implements OGDSService class which provides methods to query from OGDS database

:construction: 
The OGDSService is intended for replacing all parts of the IContactInformation utility, which contains OGDS queries. At a later date the service should also provided methods to query clients, organizational and administrative units. For the real aim, to implement the OGDSService as a independents web service.

@lukasgraf could you take a look?