Allow windows users to download Atom via the release notes view

![release notes - _users_corey_github_release-notes](https://cloud.githubusercontent.com/assets/596/3513392/43a750c0-06c2-11e4-8f44-4d7f91f87a07.jpg)

![release-notes-status-bar coffee - _users_corey_github_release-notes](https://cloud.githubusercontent.com/assets/596/3515798/19b4ff8a-06d9-11e4-9671-9ef2e6a99b7f.jpg)

How about that? I used 'Upgrade' but can change it to 'Update Available'.