enhancement for gateway connection through proxy

[muemi03]

Suggestion for the following enhancements: support for

• --options.log : overwrite log level.
• --options.port : overwrite default port given in gateway config.
• gateway connection through given proxy.

In our scenario, we are forced to use environment specific proxies to be able to connect to gateways. Example:

{
    "gateways": {
        "GW123": {
            "address": "https://mygateway-dns:8443/graphman",
            "proxy": "http://proxy-dns:8080",
            "username": null,
            "password": null,
            "rejectUnauthorized": true,
            "certFilename": "graphman-admin.crt",
            "keyFilename": "graphman-admin.key",
            "passphrase": "7layer",
            "allowMutations": true
        }
    }
}

The solution is dumb and simple. If a proxy is used, do a connect to the proxy and resuse this proxy-socket for the gateway request.