Update healthcheck
Update healthcheck

Simplify the healthcheck. We were not parsing the output of _cluster/health?pretty=true, hence no need to obtain it. Just do a simple check to / to see if elasticsearch is responding at all. Return 204 if yes, otherwise 500. The intention of _cluster/health?pretty=true was to pass the json returned by elasticsearch to user, so that they can determine themselves the health, but tsuru doesn't pass the body. Thus we return empty body.

globocom/elastic-search-api