[Feature requiest] use minor version

[regisz]

It would be great if I could use the next commnad: pyenv virtualenv 3.6 my-virtualenv-py36 And this case the latest installed py3.6 would be used. And, in the feature, the last installed py3.6 would be used even if I installed a new one. Because without this I have to recreate my every virtualenv when I would like to use the newer patch version.