Uncommented setUpIntroCheckBoxes() then project didn't build, had errors. Fixed errors by correcting onCheckChanged to onCheckedChanged.

    is not abstract and does not override abstract method onCheckedChangd(CompoundButton,boolean) in OnCheckedChangeListener
    method does not override or implement a method from a supertype

# References
https://developer.android.com/reference/android/widget/CompoundButton.OnCheckedChangeListener.html
http://stackoverflow.com/questions/10057328/cant-set-oncheckedchangelistener-to-a-checkbox
http://stackoverflow.com/questions/12466747/method-does-not-override-or-implement-a-method-from-a-supertype