Add initial CHANGELOG.md and CONTRIBUTING.md [#55] [ci skip]
Show Travis build status of `gh-pages` branch only [ci skip]
Update CHANGELOG.md to 3.1.0 [#55] [ci skip]
Improve bower.json. Details follow.

- Use unminified version.
- Add dotfiles to gitignore.
- Add keywords, homepage, description, authors, license.