Removing trash command from osx plugin

Current **trash** command implementation from osx plugin has a bunch of issues:

1. It does not have “Put Back” feature (PR #3038).
2. It does not rename files correctly whether we already have file with the same name in the Trash (PRs #3195, #3038).
3. It does not move file to proper trash on multiple drives systems (PR #3421).
4. It overrides trash command from http://hasseg.org/trash/ implementation and requires additional workaround to work with osx plugin.

@Kriechi has suggested https://github.com/robbyrussell/oh-my-zsh/pull/3038#issuecomment-52826550 to remove trash command from plugin in favor of binary trash and afair you have agreed to remove it, but it still exists.

So here is the magic PR. :blush: