Losslessly compress img/top.png.

1749 -> 698 bytes
Minor CSS tweaks.

* tabs to spaces
* be more explicit with the background properly
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