Fix Travis CI

* Remove unecessary script/cibuild
* Build drafts during Travis CI testing
* Only install rake and html-proofer for testing
* Exclude non-site files from Travis CI build
* Ignore docs/ during HTML proofing
* Add proper _config.yml
* Remove unused javascripts/main.js and params.json files

Closes https://github.com/PistonDevelopers/pistondevelopers.github.io/issues/66.