Improve docs.
Losslessly compress img/top.png.

1749 -> 698 bytes
Minor CSS tweaks.

* tabs to spaces
* be more explicit with the background properly
* remove units from zero
* remove duplicate property and non standard one (`-ms-transition`)
Properly ignore *.log files.
Improve Grunt support.

* remove clean since concat already overwrites the dist files
* improve JSHint support
* update all devDependencies
* simplify package.json and add `test` script
Update .travis.yml.

* remove node 0.8
* add grunt-cli
Update demo code to the latest online version.

Also fix the validation errors and clean up JS code.
Rename jquery.easing.min.js to reflect the fact its not minimized.
Fix JSHint issues and made code style consistent.
README.md: add devDependency badge.