fix mocha's "--compiler" option for CoffeeScript 1.7.x

use CoffeeScript 1.7.x or later, specify in package.json

use coffee&mocha command in `node_modules/.bin/`

remove node.js 0.6 and 0.8 from test target at TravisCI, CoffeeScript1.7.x not works with them.
Merge pull request #5 from shokai/fix_test_for_coffee1.7.x

fix mocha's "--compiler" option for CoffeeScript 1.7.x