Update all dependencies to their latest versions
Update `Gruntfile.js`

* Remove `grunt-contrib-uglify` as it is no longer needed.
* Remove extra commas.
* Fix typo in comment.
Remove obsolete JSHint options
Update jQuery to v1.11.0
Losslessly compress images
Add images to filerev
Use protocol relative URL for the web font
Update `index.html`

* Remove no longer needed JSHint global (`YT:false`).
* Fix typos in comments.
Add Travis CI support

Ref: https://travis-ci.org/
Add `grunt-html-validation` plugin

Additionally:

* Add a Grunt `test` target which runs the needed tasks.
* Fix existing validation errors.
README.md: Add a `devDependencies` badge

Close h5bp/html5boilerplate.com#113.