broccoli-concat merge

[stefanpenner]

this repository has been merged back into broccoli-concat (which now resides at https:/ember-cli/broccoli-concat) Having a single broccoli-concat lib should prevent some confusion in the broccoli world.

It may be a good idea to call out the deprecation in the readme.

Also, you should have both commit and release bit for the broccoli-concat lib, let me know if that is not true and you wish it to be.