[UI] Adds Wizards.

Adds AddProjectToSessionWizard and JoinSessionWizard.

Change-Id: I47c07c1ca948691b8f2ed4720ef85b09bca01e57
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1972
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Tested-by: Jenkins CI
Reviewed-by: Holger Schmeisky <google@schmeisky.com>