Change the build process

- [ ] remove yeoman and start from the scratch
- [ ] setup `grunt-contrib-coffee` (compiler for coffescripts)
- [ ] migrate sources to CoffeeScript
- [ ] setup `grunt-bower-task` (provides better integration with grunt and bower)
- [ ] setup `grunt-coffeelint` (kind of jslint for coffeescripts)
- [ ] setup `grunt-karma` for unit specs
- [ ] add some missing js specs
- [ ] setup `grunt-contrib-watch`
- [ ] handle css/less styles
- [ ] create `README` and document the build process