package.json: Use CoffeeScript 1.7.1
package.json: Use CoffeeScript 1.7.1

Tested: `npm test` will pass.

To review the changes, see https://github.com/jashkenas/coffeescript/compare/1.7.0...1.7.1
jrolfs/gulp-coffee,contra/gulp-coffee,coffee-void/gulp-coffee,stevelacy/gulp-coffee,halhenke/gulp-coffee,wearefractal/gulp-coffee,doublerebel/gulp-iced-coffee