Added Support for the enrich Method on the GeoEnrichment Service

Hello.  I've added support and documentation for the enrich method of the GeoEnrichment service.  I based the additions on the Batch geocode example.  I tried to keep the style consistent with the rest of the library, but please let me know if you think anything needs to be refactored.  Support is still needed for StandardGeographyQuery, dataCollections, and CreateReport methods.  Let me know if there's any interest to support the remaining methods.  Thanks!