[suggestion] Usage of ES2015 features available in node@4

[dignifiedquire]

As we already restrict the node version to be > 4 it seems very reasonable to me to start using the available ES2015 features shipping with v8 (list can be found here)

This means adding two things to support it:

1. Use babel-eslint parser for eslint instead of the standard one, as that supports all features needed.
2. Add babelify to the browserify toolchain to ensure the code still works in all browsers.

[daviddias]

Sounds good :) can we add it as a standard config value instead of a gulp linting rule (like this)? I feel it is more explicit and we can apply this rule across every project without forcing all the other projects to use gulp.

[dignifiedquire]

We can do that, or continue to use eslint directly, we are not forcing any project to use gulp by that, they can just use the eslint binary directly instead of calling the standard binary.