Fix version installs with justhub repo

If we specify a version of the package in the justhub repo, we need to make sure
we specify the same version for both the haskell meta package and the
haskell-min meta package. Otherwise it will still install the latest version of
ghc. Added tests to ensure the correct ghc version gets installed.
you can do
```ruby
%w[haskell haskell-min].each do |p|
  desribe package(p) do
    it { ... }
  end
end
```

here to avoid calling <code>describe</code> twice.