Remove documentation links for repo packages.

pub.dartlang.org will now automatically link to dartdocs.org for
packages with no documentation link.

BUG= http://dartbug.com/20177, http://dartbug.com/20178, http://dartbug.com/20186
R=sigmund@google.com

Review URL: https://codereview.chromium.org//416973003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/json_rpc_2@38551 260f80e4-7a28-3924-810f-c04153c831b5