Mackup zap stanza import

Add `zap` stanzas to 88 Casks based on data from the wonderful [mackup](https://github.com/lra/mackup).

I couldn't come up a clever way to leverage the mackup repo, given our current Homebrew-based infrastructure, so am importing some of the relevant data into the Cask DSL, now that we support `zap`.

Note that the `brew cask zap` verb is merged now but not yet in release.

cc @lra
`:trash` exists in the DSL now, but only works as a `:files` synonym.

The general problem is another good point.  As policy, we should document that `zap` should not delete user-created content.  On the technical side, we can add a `:rmdir` key that means rmdir-if-empty.  That way, `~/.atom` can still get cleaned up if no user content exists.