title: flutter packages get fails
body: <p>When I am trying to add <code>firebase_auth</code>, and run <code>flutter packages get</code> I get me the following error </p>
  
  <pre><code>Running "flutter packages get" in demo...
  demo firebase_auth has no versions that match &gt;=0.2.3 &lt;0.3.0 derived from:
  - demo depends on version ^0.2.3
  </code></pre>
  
  <p>I am not exactly sure what should I do to fix that.</p>
  
  <pre><code>name: full3
  description: A new Flutter project.
  
  dependencies:
    flutter:
        path: C:\flutter\packages\flutter
    google_sign_in: "^0.3.1"
    firebase_auth: "^0.2.3"
  
  # For information on the generic Dart part of this file, see the
  # following page: https://www.dartlang.org/tools/pub/pubspec
  
  # The following section is specific to Flutter.
  flutter:
    fonts:
          - family: Encode Sans
            fonts:
            - asset: assets/fonts/EncodeSansExpanded-Light.ttf
  
    assets:
    - assets/img/facebook.png
    - assets/img/google.png
    - assets/img/logo.png
    - assets/img/signup.png
  
    # The following line ensures that the Material Icons font is
    # included with your application, so that you can use the icons in
    # the Icons class.
    uses-material-design: true
    # To add assets to your application, add an assets section here, in
    # this "flutter" section, as in:
    # assets:
    #  - images/a_dot_burr.jpeg
    #  - images/a_dot_ham.jpeg
  
    # To add assets from package dependencies, first ensure the asset
    # is in the lib/ directory of the dependency. Then,
    # refer to the asset with a path prefixed with
    # `packages/PACKAGE_NAME/`. Note: the `lib/` is implied, do not
    # include `lib/` in the asset path.
    #
    # Here is an example:
    #
    # assets:
    #  - packages/PACKAGE_NAME/path/to/asset
  
    # To add custom fonts to your application, add a fonts section here,
    # in this "flutter" section. Each entry in this list should have a
    # "family" key with the font family name, and a "fonts" key with a
    # list giving the asset and other descriptors for the font. For
    # example:
    # fonts:
    #   - family: Schyler
    #     fonts:
    #       - asset: fonts/Schyler-Regular.ttf
    #       - asset: fonts/Schyler-Italic.ttf
    #         style: italic
    #   - family: Trajan Pro
    #     fonts:
    #       - asset: fonts/TrajanPro.ttf
    #       - asset: fonts/TrajanPro_Bold.ttf
    #         weight: 700
  </code></pre>