Adding Jekyll project to Travis CI

.travis.yml

language: ruby
script: "bundle exec jekyll build"

README.md

Adding a badge (change the title, user and repo, also branch, if it is not master)

# title [![Build Status][build]][build-link]
[build]: https://travis-ci.org/user/repo.png?branch=master
[build-link]: https://travis-ci.org/user/repo

Gemfile

source 'https://rubygems.org'
gem 'github-pages'