Srp

I'm creating a pull request so I can leave comments.
How do you feel about this:

```elixir
    opponent = rstrip(gets("Would you like to play against the smart computer, or the dumb computer? Please enter 'smart' or 'dumb'.\n "))
    if opponent == "smart" || opponent == "dumb" do
      opponent
    else
      get_opponent
    end
```