paper-toggle-button references PaperRippleBehavior, but changes almost nothing; is it needed?

[bicknellr]

See https://github.com/PolymerElements/paper-toggle-button/blob/e122659/paper-toggle-button.html#L246.

@notwaldorf pointed out that the class is unnecessary given that the ripple already has an id and that 'recenters' should really be 'center' in this case.