Add documentation for running Couscous in Travis #36

## [WiP]

This PR solves a little problem while running travis builds as less and less-plugin-clean-css were packages were missing.

To safely deploy with couscus from a travis build we need to take this things into consideration:

1. Make sure the build is running for master.
2. Make sure it is not a pull request.
3. Make sure we deploy once per build E.G. don't deploy for every PHP version tested :smile:
4. Decide what to use to deploy: [Private Key](http://stackoverflow.com/questions/23277391/pushing-to-github-from-travis-ci) or [Personal Access Token](http://stackoverflow.com/questions/18027115/committing-via-travis-ci-failing)  
4.1 More info on [Personal Access Token](https://medium.com/@nthgergo/publishing-gh-pages-with-travis-ci-53a8270e87db)
5. You can have a look at the latest builds of my fork in [travis-ci](https://travis-ci.org/lombartec/Couscous/builds) to see more or less what happened

Feel free to add commits and keep working on this together.