Python-SDK - 3.2.0-beta.1

## [3.2.0b1] - July 26th, 2019

## New Features:

- Added support for automatic datafile management via [PollingConfigManager](https://github.com/optimizely/python-sdk/blob/3.2.x/optimizely/config_manager.py#L151):
- The [PollingConfigManager](https://github.com/optimizely/python-sdk/blob/3.2.x/optimizely/config_manager.py#L151) is an implementation of the [BaseConfigManager](https://github.com/optimizely/python-sdk/blob/3.2.x/optimizely/config_manager.py#L32).
- Users may provide one of datafile or SDK key (`sdk_key`) or both to `optimizely.Optimizely`. Based on that the SDK will use the [StaticConfigManager](https://github.com/optimizely/python-sdk/blob/3.2.x/optimizely/config_manager.py#L73) or the [PollingConfigManager](https://github.com/optimizely/python-sdk/blob/3.2.x/optimizely/config_manager.py#L151). Refer to the [README](https://github.com/optimizely/python-sdk/blob/3.2.x/README.rst) for more instructions.
- An initial datafile can be provided to the `PollingConfigManager` to bootstrap before making HTTP requests for the hosted datafile.
- Requests for the datafile are made in a separate thread and are scheduled with fixed delay.
- Configuration updates can be subscribed to by adding the Optimizely config notification.
- Introduced `Optimizely.get_feature_variable` API. ([#191](https://github.com/optimizely/python-sdk/pull/191))

## Deprecated:

- NotificationCenter.clear_notifications is deprecated as of this release. Please use `NotificationCenter.clear_notification_listeners`. ([#182](https://github.com/optimizely/python-sdk/pull/182))
- `NotificationCenter.clear_all_notifications` is deprecated as of this release. Please use `NotificationCenter.clear_all_notification_listeners`. ([#182](https://github.com/optimizely/python-sdk/pull/182))

https://github.com/optimizely/python-sdk/releases/tag/3.2.0-beta.1