Change GWT plugin archetype to implement screen instead of dialog

We are now able to display a GWT screen when clicking on a menu item.
The GWT plugin archetype should create an example screen. So far it
was only showing a dialog.

Change-Id: I8b599542ae92e01195ce0402ae085615e86a1b62
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
7 files changed