Optimizely-sdk

Bug Fixes:
* Fixed issue with serving incorrect variation in projects containing multiple flags with duplicate keys. https://github.com/optimizely/python-sdk/pull/347
* Fixed issue with serving incorrect variation in create_impression_event in user_event_factory.py. https://github.com/optimizely/python-sdk/pull/350

New Features
* Added support for multiple concurrent prioritized experiments per flag. [322](https://github.com/optimizely/python-sdk/pull/322)

New Features
* New Features
Introducing a new primary interface for retrieving feature flag status, configuration and associated experiment decisions for users ([309](https://github.com/optimizely/python-sdk/pull/309)). The new `OptimizelyUserContext` class is instantiated with `create_user_context` and exposes the following APIs to get `OptimizelyDecision`:

- set_attribute
- decide
- decide_all
- decide_for_keys
- track_event

For details, refer to our documentation page: https://docs.developers.optimizely.com/full-stack/v4.0/docs/python-sdk.

Bug Fixes:
* Added "enabled" field to decision metadata structure. [306](https://github.com/optimizely/python-sdk/pull/306)

New Features:
* Added support for upcoming application-controlled introduction of tracking for non-experiment Flag decisions. [300](https://github.com/optimizely/python-sdk/pull/300)

New Features:
* Version targeting using semantic version syntax. [293](https://github.com/optimizely/python-sdk/pull/293)
* Datafile accessor API added to access current config as a JSON string. [283](https://github.com/optimizely/python-sdk/pull/283)

Bug Fixes:
* Fixed package installation for Python 3.4 and pypy. [298](https://github.com/optimizely/python-sdk/pull/298)