Update GameModel.swift

You can use 0..dimension instead of 0...dimension-1
Merge pull request #2 from AKSHAYUBHAT/patch-1

Update GameModel.swift

Changes:
- Changed loops to use half-inclusive (..) range operator rather than full-inclusive (...) range operator
Adding score view, general improvements

Changes:
- Added score view implementation
- More elegant code to lay out view controller
- Fixed bug with how model was tracking score
- Re-enabled alert views (thank you Sean Swezey!)
Updating readme