[UI] add dummy Notification display

This dummy class allows us to keep notification calls
in the rest of the code.

Change-Id: I38e9bd49345a80ade2f6bd77bfeae7389cae4b86
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1768
Tested-by: Jenkins CI
Reviewed-by: Arndt Lasarzik <alasarzik@gmail.com>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>