Can't set proxy.

[taka1498]

https://github.com/charltoons/hipchatter/blob/1ba1dcc2f495d4c36eac1e0ff21bc247a87d66f5/hipchatter.js#L405

This code is fixing request option, and this library is using needle. needle is fixing default request option. So user can't use environment argument to set proxy. Thereby, user can't access hipchat api through proxy.