Pyee

- Added a `BaseEventEmitter` class which is entirely synchronous and
intended for simple use and for subclassing
- Added an `AsyncIOEventEmitter` class for intended use with asyncio
- Added a `TwistedEventEmitter` class for intended use with twisted
- Added an `ExecutorEventEmitter` class which runs events in an executor
- Deprecated `EventEmitter` (use one of the new classes)

- CHANGELOG.md reformatted to CHANGELOG.rst
- Added CONTRIBUTORS.rst
- The `listeners` method no longer returns the raw list of listeners, and
instead returns a list of unwrapped listeners; This means that mutating
listeners on the EventEmitter by mutating the list returned by
this method isn't possible anymore, and that for once handlers this method
returns the unwrapped handler rather than the wrapped handler
- `once` API now returns the unwrapped handler in both decorator and
non-decorator cases
- Possible to remove once handlers with unwrapped handlers
- Internally, listeners are now stored on a OrderedDict rather than a list
- Minor stylistic tweaks to make code more pythonic

- Fix bug in setup.py; Now publishable

- Coroutines now work with .once
- Wrapped listener is removed prior to hook execution rather than after for
synchronous .once handlers

- Add universal wheel

- EventEmitter now inherits from object