pin grafana to version 4.6.0

tools/src/Release.php

@@ -703,7 +703,7 @@ class Release extends Command
 
         $composer
         ->addService($module)
-        ->image("grafana/grafana")
+        ->image("grafana/grafana:4.6.0")
         ->addLinks("mysql")
         ->restart($this->_docker_restart_default)
         ->addEnv_file("running.env")