sendRoomMessage is no longer part of the hipchat-client api.

Updating it to use new hipchat-client format in accordance to readme (https://www.npmjs.org/package/hipchat-client#readme)
```
hipchat.api.rooms.message({
  room_id: 'Frontend',
  from: 'HipChat Client',
  message: 'Hello world!'
}, function (err, res) {
  if (err) { throw err; }
  console.log(res);
});
``