Updated XeroOrganisationService
Cleaned up some code not needed
Updated to read XML as JSON dates weren't working
Got date values correctly setting
Cleaned up some code in XeroContactService
Also added in Modified since code
Updated to use method missing and convert getAllCustomers to findAllBy method
Refactored a bit so I don't repeat as much code
Tried to get caching of method working, but I don't quite understand how it works yet, need to do more research, but didn't want to remove code for future
Updated to get service property name dynamic by property name passed in