Add Prout to gu-who

Also adding continuous deployment working with sbt-heroku

http://docs.travis-ci.com/user/encryption-keys/
https://dashboard-next.heroku.com/account

```
$ travis encrypt HEROKU_API_KEY=xxxxxxxx --add
```

https://github.com/heroku/sbt-heroku
Merge pull request #36 from guardian/add-prout

Add Prout to gu-who