ignore coverage file
change blanket pattern
add two npm tasks

* add coverage task
* add coveralls task
change ignore target becauseof using coffee-coverage.

* ignore generaged files (ex. *.js, *.js.map)
* ignore directory to coverage
delete all generated files such as *.js becauseof using coffee-*

use following coffee-*

* to test -> mocha with --compiler coffee:coffee-script
* to coverage -> coffee-coverage and blanket
* to compile -> grunt coffee task and npm postinstall script