add license info to ember-cli build

I'm looking to stamp my ember-cli build files with license information.

/* 
   Each js and css file should have a comment near the top 
   with multiline license info.
*/

I see that uglify allows this behavior via the --comments option. I can set the comments flag in my ember-cli build to be passed through here. How can I pass a file containing the license comment to my app tree in ember-cli-build.js to keep this comment at the top of all the build files? Note, adding comment manually after build will invalidate source maps!

Thanks!