Cleanup grunt tasks for running specs

- [x] `grunt test:unit` - run karma without compiling coffeescripts
- [x] `grunt test:unit::coverage` - compile coffeescripts, run specs with coverage
- [x] ability to select coverage reporter `grunt test:unit::coverage --reporter=html/text`
- [x] cleanup karma config files
- [x] review other grunt tasks
- [x] `grunt test:e2e` - run angularjs e2e scenarios
- [x] `grunt test:capserjs` - run casperjs scenarios
- [x] fix https://github.com/lucassus/angular-seed/issues/41
- [x] simple script for running karma (`./script/karma`)