MXS-1929: Start monitors after creation

Monitors created via the REST API that were started and configured
successfully should also be started. This removes the extra step of
starting the monitor after creating it.

server/core/config_runtime.cc

@@ -1949,6 +1949,10 @@ MXS_MONITOR* runtime_create_monitor_from_json(json_t* json)
                 runtime_destroy_monitor(rval);
                 rval = NULL;
             }
+            else
+            {
+                monitor_start(rval, rval->parameters);
+            }
         }
     }