Ensured same behavior of MetaClass#get*Fields() implementations.

* GWTClass.#get*Fields() and BuildMetaClass.#get*Fields() now behave
  the same like JavaReflectionClass.#get[Declared]Fields()
* Added a test case for building a class with access to inherited fields

Fixes https://issues.jboss.org/browse/ERRAI-640
ERRAI-643: Make sure to trigger converters when syncing FROM_UI
Merge branch '2.4'