Fix SHA

```bash
brew install https://raw.github.com/Homebrew/homebrew-completions/master/vagrant-completion.rb
######################################################################## 100.0%
==> Downloading https://github.com/kura/vagrant-bash-completion/archive/0.0.4.tar.gz
######################################################################## 100.0%
Error: SHA1 mismatch
Expected: 94792b1d50c4c9741f96bf47404ec62dd1ebaaf1
Actual: 4ba3b0d4b0a3af9cfc72a55d32f64a9222699c63
Archive: /opt/boxen/cache/homebrew/vagrant-completion-0.0.4.tar.gz
(To retry an incomplete download, remove the file above.)
```

Fix SHA for Vagrant bash complete