Add description field to package.json
Rename readme source file

So it's not matched by read-package-json glob
https://github.com/npm/read-package-json/blob/4cf7d94815765bb6991cdc3d3112de5bf509317a/read-json.js#L234
updated available cdnjs and nuget versions in readme-src.coffee

https://github.com/baconjs/bacon.js/commit/d80f7a829676c6a6cfa252cc7f50ee4f928f1e49
Merge pull request #332 from phadej/description

Changes to make npmjs page look nicer
publich Observable.withDescription