esamesync-esame.service: create /opt/esame if it does not exists.

Otherwise the service will loop and a freshly installed machine
(or a machine with an empty /opt) will not finish the boot.

systemd-ubuntu/esamesync-esame.service

@@ -10,6 +10,7 @@ Environment=RUNLEVEL=3
 #ExecStart=/etc/init.d/esamesync esame
 User=esamesync
 Group=esamesync
+ExecStartPre=-mkdir -p /opt/esame && chown esamesync:esamesync /opt/esame
 ExecStart=/usr/libexec/labmanager/esamesync-esame.sh
 #TimeoutSec=0
 RemainAfterExit=yes