Re-order headers in WindowsAzureMobileServices.h alphabetically
Re-order headers in WindowsAzureMobileServices.h alphabetically

- Reordering headers to make it easier to manage.
- All headers should be self sufficient and should not have to depend
on any other header (a particular inclusion order) for compilation. So
an alphabetical ordering of headers should not cause any problem in the
future.

Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client,Azure/azure-mobile-apps-ios-client