Set up the structure for the mini games. This includes adding isInfected and isVisible methods to the GridView and GridModel, creating classes for the two mini game view controllers and for the mini game view controller interface, setting up the storyboard with two new view controllers, and adding some logic to the level view controller to use these additions.
This implementation has made me wonder if we should have all our mini games inherit from a base mini game view controller class instead of merely implementing a mini game view controller protocol. For now, though, I'm sticking with the protocol. I also wonder if we need the startMiniGame method, since I can't actually picture it doing anything that couldn't be done in viewDidLoad - in this case, we could omit the protocol or inherited class entirely.
Added simple view controller for the main menu.
Merge pull request #28 from zsweedyk/vc-connections

ViewController connections