Implement package redirect shortcuts

Adds two new routes:
* `/package/:name/repo` - redirects to the packages repository url
* `/package/:name/homepage` - redirects to the packages homepage

With the repository urls, there's a small amount of reformatting done in order to give a url that can be sent to the browser, rather than a git url. **Note:** Currently does not work for SSH based repository urls.

If we a encounter any errors, then we just redirect to the package page.

For where this idea came from, see: https://github.com/npm/npm-www/issues/608