Bug 6929 - ensure that koha-stop-zebra will try to stop everything

Bug 6929 - ensure that koha-stop-zebra will try to stop everything

Currently, if it attempts to stop a zebra process that doesn't exist,
the script will abort, which leaves things running. This patch prevents
it from aborting.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
(cherry picked from commit aca414977ac3f16cec353c23c59a298ee828d24c)

Signed-off-by: Chris Nighswonger <chris.nighswonger@gmail.com>