Some changes in ViewController.swift and Main.storyboard

In the Storyboard I've removed all the buttons above the imageviews and I've assigned a tag to each imageview. Then, in ViewController.swift, i've made the following changes:
1) i've created an UIImageView array to contain all of the imageviews' IBOutlets
2) in the viewFidLoad method I've created a UITapGestureRecognizer for any image to handle the touch and I've deleted the IBAction function
3) I've updated the declaration for the plays dictionary based on the release notes of Xcode beta 3
4) I've created an enum "Player" to have a proper name to differentiate the User from the AI
5) I've changed the index of the spots from 1...9 to 0...8