add registerVisibleHandler for PresenterWidget
Started on implementing rest action handlers.
Update PresenterWidget.java
Added a delegate interface to RestDispatch. The implementation hides the use of RestDispatch.
Allow resource interface methods to return the result type directly.
Added a dispatch-rest-shared module so that resource interfaces can be shared between client/server.
Added testing tools for resource delegates.
Merge pull request #585 from ArcBees/cv_rest_dispatch_delegate

Added delegates to rest dispatch and ability to return result type directly from iface methods.
Merge pull request #579 from danielkaneider/master

add registerVisibleHandler(HandlerRegistration) for PresenterWidget (patch)
Merge pull request #595 from rdwallis/poppublic

make PopupPosition ctor public
Major refactoring to the client action handler system, see below:
* Renamed the system 'client action handlers' to 'interceptors'.
* Moved the standard functionality with some enhancements to the rpc package.
* Implemented functionality for rest interceptor support.

TODO:
* Create a full set of tests to ensure it's working.
* Fix javadocs and any remnants from the previous naming convention.
Added Builder class for InterceptorContext.
Merge branch 'master' of github.com:ArcBees/GWTP into interceptors_squash2

Conflicts:
	gwtp-core/gwtp-dispatch-rest/src/main/java/com/gwtplatform/dispatch/rest/client/DefaultRestDispatchCallFactory.java
	gwtp-core/gwtp-dispatch-rest/src/main/java/com/gwtplatform/dispatch/rest/client/DefaultRestDispatchHooks.java
	gwtp-core/gwtp-dispatch-rest/src/main/java/com/gwtplatform/dispatch/rest/client/RestDispatchCall.java
	gwtp-core/gwtp-dispatch-rest/src/main/java/com/gwtplatform/dispatch/rest/client/gin/RestDispatchAsyncModuleBuilder.java
	gwtp-core/gwtp-dispatch-rpc-client/src/main/java/com/gwtplatform/dispatch/rpc/client/DefaultRpcDispatchCallFactory.java
Keep backwards compatibility for ClientActionHandler's.
Merge pull request #597 from BenDol/interceptors_squash2

Replace 'Client Action Handlers' with 'Dispatch Interceptors'
Carried all ctors from PopupViewImpl to PopupViewWithUiHandlers
Fixed generic in success delegate stubber
Merge pull request #599 from ArcBees/fix_success_delegate_stubber

Fixed generic in success delegate stubber
Merge pull request #598 from ArcBees/abstract_popup_view_ctor

Carried all ctors from PopupViewImpl to PopupViewWithUiHandlers
type safe slots