Cleanup
Also made it so the ConverterFieldAdapter takes a generic which extends
the gxt component class as well as IsField.
Need to convert the AppWizardDiskResourceSelector to a normal field.
This field will be wrapped with a ConverterFieldAdapter.
As a field, it will be an Editor<String>. The splittable conversions
will be handled via converters.
The hierarchical list selector also needs to become a field.