Changing menuRadius after `init`moves bubble pivot

[shrugs]

Changing menuRadius after initializing the LIVBubbleMenu makes weird stuff happen because the frame is not recomputed. To fix, you'd need a custom setter that recomputes frame. This is not a critical bug, though, because the menuRadius can be set during initialization.

bubbleMenu = [[LIVBubbleMenu alloc] initWithPoint:somePoint radius:75.0f menuItems:self.images inView:self.view];
bubbleMenu.menuRadius = 100.0f;
[bubbleMenu show];