Update signatures for EventEmitter.

Allow for method chaining in addListener/removeListener, on/once,
and removeAllListeners.

Fix return type for 'emit'.

This patch mirrors the changes made to the API docs in this commit:
https://github.com/joyent/node/commit/41cbdc5e64d090e0708dd2a63d4cd63000019bb1
Merge branch 'update-EventEmitter' of https://github.com/duncanmak/DefinitelyTyped into duncanmak-update-EventEmitter
fix(jake) fix definitions to match new node definitions
fix(browser-harness) fix for new definitions of nodejs
fix(threejs) tests do not compile with --noImplicitAny