SoycDashboard has been deprecated for a while now, time to remove gwt:soyc
BrowserManagerServer and RunStyleRemoteWeb have been removed in GWT 2.7
Update dependencies and plugins, simplify POM a bit, require Maven 3+
Simplify artifact retrieval (from plugin dependencies)

TODO: pick gwt-user from project deps where it probably is already.
Cleanup the "new" JavaCommand, merge JavaCommandRequest into JavaCommand.
Finally remove "old" deprecated JavaCommand
Fix (actually use) sourceLevel handling in gwt:run
Delete old unused files (that should have never been added to Git)