Working on request model object.
Added DFGWaterReading.  Added DFGWaterGaugeDataRetrieverDelegateProtocol.
Added nonatomics.
Added methods to DFGWaterGaugeDataRetrieverDelegateProtocol.
- Added DFGError.
- Starting DFGWaterUSGSGaugeDataRetriever.
- Added DFGWaterGauge model.
- Started DFGWaterServiceRequestBuilderProtocol and
  DFGWaterUSGSIVRequestBuilder implementation.
- Modified DFGWaterReading to have units.
Starting an integration test.
Integration test is sleeping for five seconds and logging a string.
- Properly centralized and using designated initializer on
  DFGWaterGaugeDataRequestParameters.
- Starting to flesh out DFGWaterUSGSIVJSONRequestBuilder.
Fleshing out the DFGWaterUSGSIVJSONResponseParser.
- Added DFGWaterReadingGroup.
- Adjusted DFGWaterServiceResponseParserProtocol and
  DFGWaterUSGSIVJSONResponseParser to return a reading group.
- Added description implementation to DFGWaterReading.
- As of this commit, retrievals for single reading and numDaysAgo readings are
  working as expected.
- Added error parameter to DFGWaterServiceResponseParserProtocol.
- Passing back readings and unavailability of readings for height, precip and
  discharge from DFGWaterGaugeDataRetrieverDelegateProtocol.
- Basic delegate method call checks -- should be using mocks, though.
- Fixed delegate method name to use withParameters: for consistency.
- Added sinceDate / endDate usage in DFGWaterUSGSIVJSONRequestBuilder.  Fixes
  #1.
- Added integration test for since/end dates.
- Moved some headers to public.
- Added class method to easily create DFGWaterGauges.
- Working from iOS app!
Added DFGWaterReading.h to DFGWater.h.
Delegate messages from DFGWaterUSGSGaugeDataRetriever now sent on main thread.
- Using armv6, armv6.
- Added [DFGWaterReading valueAsDecimalNumber].
Initial addition of gauge finder classes and protocols.  Changed "Half Off
Depot" occurrences to "D5G Technology, LLC".
Fixed finder delegate protocol name and references to it.  Made finder protocol
forward-declare DFGWaterGaugeFinderContext instead of importing it.