Installation issues - Suggestions to help improve the experience.

Many people are familiar with swift but I don't believe that many will be familiar with the nuances of setting up a WK app. Even if you are not trying to load it onto a watch the fact that an app group is used complicates things quite a bit.

In my case I had to refresh my understanding of WK to get everything up and running - I hope to save others some time.

1. Change case sensitive suffix test to case insensitive:
change `if fileURL.absoluteString.hasSuffix(".jpg") || fileURL.absoluteString.hasSuffix(".png")`
to `if fileURL.absoluteString.lowercased().hasSuffix(".jpg") || fileURL.absoluteString.lowercased().hasSuffix(".png")`

Files: `BackgroundViewController.swift`, `ViewController.swift`, `InterfaceController.swift`

2. Add instructions to readme explaining that the developer will need to make their own app ids for the `app`, the `wk app`, and the `app extension` and will need to make their own `app group`.
3. Add instructions to readme explaining the locations where the app group needs to be changed to the new one created by the developer.

Files: `PhotoWatch.entitlements`, `PhotoWatch WatchKit Extension.entitlements`, `BackgroundViewController.swift`, `PhotoViewController.swift`, `InterfaceController.swift`

- Thanks,

Jim Malak - jim.malak@beryle-lee.com