Failure installing npm dependency specified with full URL

I have created an ember-cli heroku instance:

heroku create xxx-yyy-uuu --buildpack http://ift.tt/1kkWazm

And deployed to it:

git push heroku

But it fails:

remote: bower ember#^2.0.0        invalid-meta ember is missing "ignore" entry in bower.json                                                                                                                 [6/2258]
remote: bower ember#>=1.4         invalid-meta ember is missing "ignore" entry in bower.json
remote: bower ember#> 1.5.0-beta.3     invalid-meta ember is missing "ignore" entry in bower.json
remote: -----> Cleaning up node-gyp and npm artifacts
remote: -----> Building Ember CLI application production distribution
remote: 
remote: Missing npm packages: 
remote: Package: ember-cli-simple-auth-token
remote:   * Specified: git://github.com/jpadilla/ember-cli-simple-auth-token.git
remote:   * Installed: (not installed)
remote: 
remote: Run `npm install` to install missing dependencies.
remote: 
remote: 
remote:  !     Push rejected, failed to compile Ember CLI app
remote: 
remote: Verifying deploy....
remote: 
remote: !       Push rejected to xxx-yyy-uuu.
remote: 
To http://ift.tt/1kkWcaA
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'http://ift.tt/1kkWcaA'

How can the npm package be installed?