Photo picker updates

Overview
1. Don't try and tap 'Choose' after picking an image
2. Documents that photo picker `row:` and `column:` parameters are 1-indexed
3. Backfills a test

Notes:
1. This does not occur in the standard `UIImagePickerController`. If a developer's test fails because of it they should add in the dismissal themselves.
2. They read like 0-indexed params so I figured it could help someone to document it.
3. The test works because on all iOS 8+ simulators the default photo pickers comes with the same 5 images. The test asserts that the selected image's size is set to the screen's label correctly.