Test registerEnumTransform on Adapter class instead of adapter instance

As the registerTransform is call on the class, the registerEnumTransform should operate on the class as well
Allow call to registerEnumTransform on Adapter class, fix #786
Fixed non camelCase variable
Merge pull request #787 from bobbus/fix-register-enum-transform-on-class

Allow calling registerEnumTransform on the Adapter class