Update libraries

@emachnic: since msysgit is now on GitHub, I get download failures probably because the link redirects to the s3 server. So I left Git to v1.8.4 for now. Not sure how to work around this.

(https://github.com/msysgit/msysgit/releases/download/Git-1.9.2-preview20140411/PortableGit-1.9.2-preview20140411.7z)

Also, can we get 2.0 and 2.1 releases out? Let me know and I can make the PRs as long as we have the Ruby binaries on S3.

TODO:
- [ ] Update Git to 1.9.2
- [x] Update Ruby to 1.9.3 p545