Remove second undelegation of hammer events

Second undelegation of hammer events is not necessary.

Every invocation of `delegateEvents` invokes `Backbone.View::delegateEvents` which in turn invokes `undelegateEvents`, undelegating all hammerEvents.

Calling `undelegateHammerEvents` in `delegateHammerEvents` could still be necessary when `undelegateHammerEvents` is invoked directly - which i guess it never should.