/bin/stop-supervisor fails in posix shell since the standard read utility
takes at least one variable's name as argument.
Changing the header #!bin/sh to #!/bin/bash fixes this issue.
`read` with no variable's name works in bash.
Looks like the shell in alpine isn't POSIX-compliant so we didn't
encounter this issue on alpine.
Also, I changed the name from "processes" to "processes-exit-eventlistener"
to make it clearer in the logs since supervisord spawns event listeners as
separate processes.
Change-Id: Ife9378c2013e2eb54f2adcd52a163d64eaacbbab
9751ac9de2