Fix Debian init script stopping

Remove "--exec ${JAVA}" as /usr/bin/java should be a symlink, so when
start-stop-daemon goes looking for Repose with a PID equal to
/var/run/repose-valve.pid and a /proc/PID/exe linking to
"/usr/bin/java", it won't find it because /proc/PID/exe will instead
be pointing to what the /usr/bin/java symlink resolves to (eg readlink
-f /usr/bin/java).  Worse yet, start-stop-daemon won't return an error
because it was told "--oknodo".

Remove "-- ..." too because "--stop" doesn't accept arguments for the
process it's trying to stop (only "--start" does that).

See start-stop-daemon man page.