Adds test for marshalling of Service Categories
Changes UsagePointSteps to use StepUtils flattenXml helper
Adds download of xml UsagePoints with Service Categories
Simplifies feature XML checks with XMLUnit
Refactors AtomMarshallerService into ATOMMarshaller and FeedBuilder.
Refactors feed controllers to use UsagePoint service.
Refactors EspiMarshallerService into EspiMarshaller util.
Code review updates
Merge pull request #1 from energyos/download-service-category

Download service category