Fix #91: Implement Gem#state

Work In Progress.

Currently implements

<img src="https://rawgit.com/wiki/ManageIQ/polisher/states.svg" />
prefer the :check be something like :any_version.

I think the conditional below read more like english like this:

```ruby
if !args[:any_version]
```

and later...
```ruby
return :needs_build if !args[:any_version]
```