[API] Adds LeaveAndKickHandler

This class is a 1:1 copy of the eclipse counterpart.

Change-Id: I393f1233d7e423209371d5e95544fef9aba812fd
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1924
Tested-by: Jenkins CI
Reviewed-by: Damla Durmaz <ddurmaz88@gmail.com>
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>