Display output URLs as hyperlinks in Hipchat

By default the output URLs are displayed in Hipchat as plain text and must be copy pasted into a browser. This change allows Hipchat to transform them into clickable hyperlinks (by default, you can turn it off).

![example](https://f.cloud.github.com/assets/591257/7674/a6e8f1d6-4434-11e2-800a-1e52bb14fb82.png)

*Tech Notes*
Hipchat now allows API messages to be processed similar to user messages by passing `message_format: text" in the API call.

[Relevant Hipchat Blog Post](http://blog.hipchat.com/2012/07/10/a-simple-but-powerful-change-to-our-messaging-api/)
[Relevant Hipchat API Docs](https://www.hipchat.com/docs/api/method/rooms/message)