Bug 17814: koha-plack --stop should make sure that Plack really stop

Bug 17814: koha-plack --stop should make sure that Plack really stop

koha-plack --stop doesn't ensure that Plack was really stopped before
returning

So in case that koha-plack --stop was quickly follows by koha-plack
--start (e.g. logrotate), it could leave Plack in stop state. This is
due to koha-plack --start think that Plack was already started, while it
actually is being stopped.

For me I think this is the cause why I got random Plack stop when
logrotate is run.

It should be similar to the case of Zebra in Bug #16885, and the
solution might be the same: adding "--retry=TERM/30/KILL/5;" to
start-stop-daemon command.

TEST PLAN
---------
1) Login to staff client and do something that will hold connection for
a long time, e.g. a batch import or a slow report.
2) sudo koha-plack --stop mykoha
3) ps aux | grep plack   <-- a Plack process will still running work in
1)
4) wait for 1) to finish and all Plack processes exit
5) sudo koha-plack --start mykoha
6) apply the patch
7) repeat step 1)-2)
8) ps aux | grep plack   <-- There should be no Plack process running
now
9) Note that work in step 1) might get terminated midway. Since we force
Plack to stop after some wait.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Mason James <mtj@kohaaloha.com>