Add versioned dart@1 formula for legacy applications (#53)
Add versioned dart@1 formula for legacy applications (#53)

This will be a manually-maintained formula that always points to the
legacy Dart 1 SDK, so old applications that haven't been upgraded
to Dart 2 can still be packaged with dependencies against it.
dart-lang/homebrew-dart,dart-lang/homebrew-dart,dart-lang/homebrew-dart