Add positional argument support

Fix key composer overriding for class methods

Support aioredis2 / super()

`ring.aioredis` supports aioredis>=2.0.0
Allow `super()`

Fix RuntimeError when eventlet.monkey_patch() done

thanks to @ohduran

Fix asyncio.coroutine usage for python 3.8+

- also fixed install_require to fit environment markers

Thanks to @yangroro for every fix.

Fix python 2.7/3.9 support

- Fix python2 errors related to typing
- Fix python3.9 errors related to asyncio.Lock

Drop Python3.4 and fix bugs

- fixed set type support
- fixed lru cache maxsize option
- fixed varargs support
- added basic Config object for future runtime configuration

contextvars support and bug fixes

- contextvars support for py3.7
- Fix ring.lru cache clear bug
- Fix staticmethod support

LRU, redis hash, dataclass support

Property support