Use config hook for config

[kimroen]

Use this: https://github.com/ember-cli/ember-cli/blob/master/ADDON_HOOKS.md#config

Instead of the home-made, free-range, organic implementation here:

ember-cli-coffeescript/index.js

Lines 16 to 24 in 3d2d409

	getConfig: function() {
	var brocfileConfig = {};
	var coffeeOptions = defaults(this.project.config(process.env.EMBER_ENV).coffeeOptions || {},
	brocfileConfig, {
	blueprints: true
	});
	return coffeeOptions;
	},

[kimroen]

The default implementation seems fine, so it should be enough to just make a file with the defaults and place it in /config.

[kimroen]

I haven't done this yet, because we don't have any tests, and I'm not confident I would catch all possible use cases of the config. Still not sure how to go about testing that.

[kimroen]

There's a related question here - at some point it was pretty clear that we were moving in the direction of having config in the config folder, but since the ember-cli-build.js file was introduced, it seems more fitting to have this kind of config in that file.

Not sure what to do about that.