Allow EntityProxy, ValueProxy, or any simple value type to be used as an entity's id and version values.
Allow RequestFactory to work with inner classes to make self-contained tests easier to write.
Resolves issue 5368.
Patch by: bobv
Review by: rchandia, rjrjr

Review at http://gwt-code-reviews.appspot.com/1127801


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9261 8db76d5a-ed1c-0410-87a9-c151d255dfc7