Moved client-side producers into top-level types

This should reduce the confusion that could be caused by keeping them in the GroceryListClient class.
Added an extra helpful hint to the "widget class is unknown to gwt" exception
Added some friendly documentation to help people get their bearings on this demo
Automated doc download + addition of language attributes

Moved the XSLT step into the new antrun section to be sure that the procedure if downloading and transforming
the docs happens in the correct sequence.
Added local docbook catalog to speed up the XSLT language attribute processing step
Updated docs for 2.2.0.CR2
data-binding: ensured property change handlers fire during state sync even when property is not bound to a widget
Removed duplicate weld-servlet-core dep. from JPA demo poms
Made downloading of fresh docbook optional.
Updated Quickstart guide for 2.2.0.CR2
Updated versions for 2.2.0.CR2
Back to 2.2.0-SNAPSHOT
Fixed invalid HTML in generated javadoc (was causing validation error)
Resolved ERRAI-460: Marshalling includes invalid generic declaration in ServerMarshallingFactoryImpl
Fixed ERRAI-463: Nested type params on maps don't work
minor javadoc fix