Updated ElectricPowerUsageSummary and UsageSummary

Added extended summary and clarifying descriptions.
Merge pull request #178 from MartyBurns/master

Updated ElectricPowerUsageSummary and UsageSummary
Fixed CreateUser issue
(https://github.com/energyos/OpenESPI-DataCustodian-java/issues/194 &
https://github.com/energyos/OpenESPI-ThirdParty-java/issues/119)
Merge pull request #179 from jateeter/master

Fixed CreateUser issue