Fix for date serialization problem in JsonRequestProcessor. Datanucleus returns custom subtypes of java.util.Date from the datastore, which causes Dates to be serialized as english strings.

Review at http://gwt-code-reviews.appspot.com/790801


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8619 8db76d5a-ed1c-0410-87a9-c151d255dfc7