Prevent bottom content inset from being negative.

On an iPad with a hardware keyboard and the shortcuts bar enabled:

If the scroll view has a bounds of:

CGRectMake(0, 138, 787,  327)

and the keyboard has a bounds of:

CGRectMake(0, 713, 1024, 55)

Then the bottom inset ended up being -107, which would make the bottom content of the scroll view inaccessible.

# Conflicts:
#	TPKeyboardAvoiding/UIScrollView+TPKeyboardAvoidingAdditions.m

TPKeyboardAvoiding/UIScrollView+TPKeyboardAvoidingAdditions.m

@@ -345,7 +345,7 @@ - (UIEdgeInsets)TPKeyboardAvoiding_contentInsetForKeyboard {
     if (keyboardRect.size.height == 0) {
         newInset.bottom = state.priorInset.bottom;
     } else {
-        newInset.bottom = keyboardRect.size.height - MAX((CGRectGetMaxY(keyboardRect) - CGRectGetMaxY(self.bounds)), 0);
+        newInset.bottom = MAX(keyboardRect.size.height - MAX((CGRectGetMaxY(keyboardRect) - CGRectGetMaxY(self.bounds)), 0), 0);
     }
 
     return newInset;