Fix: Button positioning when horizontal

• Gave proper bottom-left-pinned and bottom-right-pinned layout to the buttons and labels along the bottom of the view in Main.storyboard.
QBPopupMenu arrow coloring & logic revision

• Revised how the `textColor` on QBPopupMenu propagates to its child views.  Now instead of being set on the children, the children ask QBPopupMenu for its `textColor` when they need it.  To accomplish this:
	◦ QBPopupMenuItemView and QBPopupMenuPagenatorView now require a QBPopupMenu reference is passed to the each initializer method, which is stored weakly and readonly.
	◦ QBPopupMenuItemView now sets up KVO QBPopupMenu’s textColor and reacts to changes by setting its button’s titleColor.
		» Instead of trying to set its buttons textColor at a exactly the right times, which wasn’t working out so well.
	◦ QBPopupMenuPagenatorView just uses `self.popupMenu.textColor` within `- drawArrowInRect:direction:highlighted:`, which is about as good as we can do.
• Fixed what seems to be a bug in QBPopupMenu’s `- showInView:targetRect:animated:`’s Calculate width section where the calculations for QBPopupMenuArrowDirectionLeft and Right seemed reversed.  Fix was to swap the two `case`s.

Also:
• Set ViewController’s popup arrowDirection to Left so that the menu extends along the bottom to the right— much cooler.