Update exim.conf

Update to CentOS 7 comand!

install/rhel/7/monit/exim.conf

@@ -1,3 +1,3 @@
 check process exim with pidfile /var/run/exim.pid
-    start program = "/etc/init.d/exim start"
-    stop program  = "/etc/init.d/exim stop"
+    start program = "/usr/bin/systemctl start exim"
+    stop program  = "/usr/bin/systemctl stop exim"