Add a dummy user with uid 1000

I find the usage of `fig` fantastic and created aliases to run ember easily:

    alias ember='fig --file ~/.ember-cli.fig.yml run --rm ember'

Yet, files created with `ember new my-app` are all owned by root. To prevent this, I created a new image from yours with a dummy user having the same uid as me. I modified the fig.yml file to run as this dummy user:

    # Copied from https://registry.hub.docker.com/u/geoffreyd/ember-cli/
    # Allows using ember-cli without installing npm and bower
    
    ember: &defaults
      image: cbliard/ember-cli
      volumes:
        - .:/usr/src/app #if your on docker actual
    
    server:
      <<: *defaults
      command: server --watcher polling
      ports:
        - 4200:4200
        - 35729:35729
    
    npm:
      <<: *defaults
      entrypoint: ['/usr/local/bin/npm']
    
    bower:
      <<: *defaults
      entrypoint: ['/usr/local/bin/bower', '--allow-root']

Now when I run `ember new my-app`, the created files have the expected owner/group.

User mapping is planned for Docker, but for the moment it has been a useful hack for me.