Remove unneeded cache variable
Fix whitespace
Update documentation
Switch from JSHint to ESLint
Update ESLint definition
Remove ability to call once() without a parameter
Add test to make sure an error is triggered when ID is missing
Merge pull request #16 from theodoreb/once-id-required

Remove ability to call once() without a parameter
Update to 2.0.0-alpha.9
Update jquery.once.js
Update CoffeeScript source