Remove jad

It's also in homebrew-binary, and adding that tap warns me of the
conflict:

```
$ brew tap homebrew/binary
[...]
Warning: Could not tap homebrew/homebrew-binary/jad over homebrew/homebrew-boneyard/jad
Tapped 15 formula
```

I'm integrating what's missing from here in homebrew-binary in
Homebrew/homebrew-binary#104.

Closes #23.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>