Adds LICENSE.md to addon blueprint
use addPackagesToProject instead of addPackageToProject in a Promise.all
Merge pull request #2522 from jakecraige/fix-test

use addPackagesToProject instead of addPackageToProject in a Promise.all
Merge pull request #2521 from twokul/addon-license

Adds LICENSE.md to addon blueprint
add Addon.prototype.isEnabled for an addon to exclude itself from the project