Adds ElectricPowerQualitySummary to fixture data xml file.
Adds feature steps and view for ElectricPowerQualitySummary
Adds domain model changes and tests for ElectricPowerQualitySummary
Renames UsagePointBuilderElectricPowerSummaryTests
Adds unmarshalling of ElectricPowerQualitySummaries from an atom feed.
[Finishes #56054346]
Cleans up some UsagePointBuilder redundancy