updated grafana.ini to support /grafana reverse proxy

Author: janvda

grafana/config.ini

@@ -4,5 +4,8 @@ provisioning = /etc/grafana/provisioning
 [server]
 enable_gzip = true
 
+# http://docs.grafana.org/installation/behind_proxy/
+root_url = %(protocol)s://%(domain)s/grafana/
+
 [users]
 default_theme = light