Fix for problem with unbinding events inside cb

When doing something like this:
.on('evt', function theCallback(data){
    this.off('evt', theCallback);
});

stapes will throw an error because the event handler array 
is being modified as it is looping though.

This edit copies the array locally to fix this.
Merge pull request #30 from wellcaffeinated/patch-2

Fix for problem with unbinding events inside cb