Use given host name prior to the host specified by an environment variable DROONGA_ENGINE_HOST.
Use given host name prior to the host specified by an environment variable DROONGA_ENGINE_HOST.

To support multiple connections, the global environment variable have to be ignroed.

droonga/express-droonga,KitaitiMakoto/express-droonga,KitaitiMakoto/express-droonga,droonga/express-droonga