The reason bug #1860155 was triggered was because the kill script did
not have a stanza for handling the signal that was passed in, which is
signal 15. Since signal 15 is unhandled, keepalived processes will
still stick around. Add handling for signal 15.
Change-Id: I632a3ef5ec137df10f647335f6354589c2316fd0
Related-bug: #1860155