Added ButtonListViewController to handle lists of toggle buttons (uses a
multi-selection enabled collection view)
Provides methods to set button label data, and count correct answers.

Modified AppDelegate to show ExampleTextVC (which uses ButtonList) to
show off a bit.
Merge branch 'master' of https://github.com/JackMF/Dementia
Adding alertview to ExampleTest to show how many correct answers
(demoing buttonList).