JSHint defaults to ES5

As stated in [1], from 2.0.0 JSHint defaults to es5: true. Moreover, if it's set to true in the configuration, it throws a nasty warning [2]

Keep up the great work, cheers,
Federico

[1] http://www.jshint.com/blog/2013-05-07/2-0-0/
[2] https://github.com/jshint/jshint/issues/1137