Revert "add versions and constraints for packages and samples"
Revert "add versions and constraints for packages and samples"

This is currently blocking us from testing samples.

BUG=
R=kasperl@google.com

Review URL: https://codereview.chromium.org//59513007

git-svn-id: c53bd6455474c0a826d309663cf600546f7b0963@29960 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/watcher