webadmin: Parameterize commonly used events

Parameterized the common events in EntityModel and in ListModel, to
help people get rid of warnings if they properly parameterize their
own listeners.

Change-Id: I3fb6f78d9b917635108c2ca4dac5af2338ee4dc0
Signed-off-by: Lior Vernia <lvernia@redhat.com>