Dump dependency version for cookiejar.

The `cookiejar` dependency is out by 2 minor versions, which solve a few bugs in that package such as https://github.com/bmeck/node-cookiejar/pull/6

The author has recently `published` a new version to `npm`: https://github.com/bmeck/node-cookiejar/issues/12

fixes: https://github.com/visionmedia/superagent/issues/174