Add checks for whether a view has constraints added to it or not

[theextremeprogrammer]

Highlights:

• Throw an error (in tests that check for that view) if the view does not have any constraints added
• Include this in a superclass so that it applies to all views and doesn't need to be added to each view type (UILabel, UIButton, etc).
• Test this using an array of different view types and a Quick test which can be applied to all of them and just use 2-3 view types as examples (UILabel, UIButton, UITextView, etc).

See also related #67