Simulating behavior of a simple button

[xinatanil]

In some cases, we need BoomMenuButton to behave as a simple button, i.e. don't display any animations.
After looking around in the code, I wasn't able to find a way to do that 😫.

I suggest that we adjust these two BoomDelegate methods from:

func boomMenuButtonWillBoom(boomMenuButton bmb: BoomMenuButton)
func boomMenuButtonWillReboom(boomMenuButton bmb: BoomMenuButton)

to

/// If delegate method returns `false` then boom won't even start
func boomMenuButtonWillBoom(boomMenuButton bmb: BoomMenuButton) -> Bool
/// If delegate method returns `false` then reboom won't start
func boomMenuButtonWillReboom(boomMenuButton bmb: BoomMenuButton) -> Bool