support mocha require multi modules in cli

support mocha cli command like this:

```
mocha -r should -r blanket --report travis-cov test/*.test.js
```
Fixing fs.existsSync issues in older versions of node
Merge pull request #375 from jonathanKingston/master

Fixing fs.existsSync issues in older versions of node
Merge pull request #371 from dead-horse/support-multi-mocha-require

support mocha require multi modules in cli
Update Grunt to v4.0
Update vendor files
Fix .travis.yml / Ignore temporary directory
Remove grunt.util.async / Fix the path to CoffeeScript compiler

* grunt.util.async is deprecated.
* See http://coffeescript.org/#changelog for details about CoffeeScript
1.7.0.
Fix coding styles according to JSHint

trailing whitespaces, unused variable declarations, and missing
semicolons
Add license statement for falafel

falafel is licensed under the MIT license