MXS-1446: Move failover to mysqlmon

Split the state change processing and failover handling into two separate
functions and added a call to the failover function into mysqlmon. This
prevents unintended behavior when failover is enabled for non-mysqlmon
monitors. The parameter itself still needs to be moved into mysqlmon.

Moved the failover documentation to the mysqlmon documentation as it is
specific to this monitor.

server/modules/monitor/mysqlmon/mysql_mon.c

@@ -1401,6 +1401,7 @@ monitorMain(void *arg)
          * need to be launched.
          */
         mon_process_state_changes(mon, handle->script, handle->events);
+        mon_process_failover(mon);
 
         /* log master detection failure of first master becomes available after failure */
         if (root_master &&