* Rework argument parsing to allow options after exec and run
* Add option for run and exec to download missing version
* Reword download to cover wider functionality
* Be consistent with inner spacing of arrays
* Add download test for run and exec
* Add support for auto, reading version from .node-version
* Make version unique in tests
* Add support for auto doing a lookup for unresolved version
* Make auto description more consistent in style with other labels.