Crash when not using ecmascript6

[yuxal]

Tried to run with an older version of node, crashed on unexpected syntax on ecma6 features.

Need to use babel

[brillout]

Because of the eject commands I'd rather keep the code written with ES6.

Added code a20a98b that tells the user to update her Node when she uses an unsupported Node version.

Let me know if you can't update your Node installation or if you have a reason not to.

[yuxal]

Already did, just thought it'd be nice to have.