Import post-build to commit to gh-pages

Post-build script imported from
https://github.com/wet-boew/wet-boew/blob/master/build/post_build.sh
Travis: use stable node.js (0.10)
Add secret GH_TOKEN to .travis.yml
Configure travis for auto-deployment

On successful deployment, travis updates the github pages (branch
gh-pages) with the content of public_html.
Merge branch 'master' of https://github.com/gallardo/obimp