Make mojo and sky dart packages deployable

The packages produced from this CL were deployed
as v0.0.1:
https://pub.dartlang.org/packages/sky
https://pub.dartlang.org/packages/mojo

There is still no tool included with the sky
package due to pub's inability to run anything
other than Dart:
https://code.google.com/p/dart/issues/detail?id=22877

I'm likely just going to write a dart version
of my "sky" script. :(

R=ojan@chromium.org, abarth@chromium.org

Review URL: https://codereview.chromium.org/1015833002

packages/flutter/pubspec.yaml

+name: sky
+author: Chromium Authors <sky-dev@googlegroups.com>
+description: Dart files to support executing inside Sky.
+homepage: https://github.com/domokit/mojo/sky
+version: 0.0.1
+dependencies:
+  mojo: '>=0.0.1 <1.0.0'