Fix git repo size

Because git is immutable, simply removing a file is not sufficient: https://github.com/Webtrends/rundeck/commit/c9a5625815668bc4669e7266188b5b12ad983a8b

I used git-filter branch to remove all _cookbooks/*_, _**/*.gem_, and _**/*.deb_:

```bash
git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch cookbooks/*' --prune-empty --tag-name-filter cat -- --all
git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch **/*.deb' --prune-empty --tag-name-filter cat -- --all
git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch **/*.gem' --prune-empty --tag-name-filter cat -- --all
```

This makes the repo ~25MB, instead of ~260MB.

The "diffs" below are probably in error, because of the nature of filter-branch.

Passes `rake`.