update mackerel-plugin-rabbitmq for setting password via environment variable.
update mackerel-plugin-rabbitmq for setting password via environment variable.

ariarijp/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,ariarijp/mackerel-agent-plugins,ariarijp/mackerel-agent-plugins,y-kuno/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,y-kuno/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,y-kuno/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,ariarijp/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,y-kuno/mackerel-agent-plugins