Automatic execution for ZSH

This release bring you an ability to execute ah t with whitelisted commands automatically. Currently for ZSH only but I will try to make support for Bash if I will find a good way to do it (maybe you know how to do it? Contributions are welcome!)

Readme is updated so please find a description at the end.

This release is built with Go 1.4rc1. I have no problems but if you will find them, please fill the issue immediately!