Miscelaneous cleanup.

Remove extra spaces from various elements within ReadingType, UsagePoint and ElectricPowerUsageSummary generated by GreenButtonDataSetGenerator.xlsm.

Remove utility reference from MonthlyOnlyElectricData.xml generated file.

Remove the following outdated files:

ESPIRender_xslt1.xslt
GBESPIRender_xslt1.xslt
CustEUI_ID0279.xml
CustEUI_ID0279.zip
CustEUI_ID1532.xml
CustEUI_ID1532.zip
CustEUI_ID7210.xml
CustEUI_ID7210.zip