Splitio-client

- Added local impressions deduping. Defaulting to optimized
- Added support for the new Split streaming architecture. When enabled (default), the SDK will not poll for updates but instead receive notifications every time there's a change in your environments, allowing to process those much quicker. If disabled or in the event of an issue, the SDK will fallback to the known polling mechanism to provide a seamless experience.
- Updated logging structure so that it's built in terms of a hierarchy with the root at 'splitio'
- Fixed timing issue which caused factory.ready to return False if called immediately after .block_until_ready()

- Updated mmh3cffi to version 0.1.5 which fixes xcode12 issue

- Added support for enabling in-memory cache via config options

- Removed enum34 dependency for python versions > 3.4

- Fixed input validation performance issue.

- Added logic to fetch multiple splits at once on get_treatments/get_treatments_with_config.
- Added flag `IPAddressesEnabled` into config to enable/disable sending machineName and machineIp when data is posted in headers.