Add options argument to robot.http

This adds the options argument that is part of the [create call/constructor](https://github.com/technoweenie/node-scoped-http-client/blob/4d0807defe6e65a022cca0a6302e1cc895a1f86c/src/index.coffee#L171-L172) from the [scoped http client](https://github.com/technoweenie/node-scoped-http-client).