Full 100% coverage

[yanickrochon]

• Domain testing (perhaps "borrow" from Node's EventEmitter tests)
• RemoveListener not fully covered
• RemoveAllListeners not fully covererd

[yanickrochon]

Domains have been deprecated, and should no longer require to be tested. (yay!)

[safizn]

The core event emitter is so primitive. I will be using this module for a while, saved me time, thank you.