Enable ES6

[pamo]

Description

Update JSHint to allow ES6.

Motivation

The support for ES6 has grown a lot. There's no need to do transpilation to use its features. http://kangax.github.io/compat-table/es6/

Expected Behavior

Use es6 features such as arrow functions in development and see that the application is interpreted by all browsers.

Actual Behavior

Build fails because we haven't enabled es6. The application runs properly in chrome.

[Roshanjossey]

@pamo, are we planning to remove JSHint and have eslint instead?

@glauberramos, have you started working on this?

[pamo]

@Roshanjossey that's even better

[glauberramos]

@Roshanjossey I didn't start it, please go ahead if you want to work on it