Android-SDK - 2.0.0-beta2

## 2.0.0-beta2

May 17th, 2018

This major release of the Optimizely SDK introduces APIs for Feature Management. It also introduces some breaking changes listed below.

### New Features
* Introduces the `isFeatureEnabled` API to determine whether to show a feature to a user or not.
Boolean enabled = optimizelyClient.isFeatureEnabled("my_feature_key", "user_1", userAttributes);

* You can also get all the enabled features for the user by calling the following method which returns a list of strings representing the feature keys:
ArrayList enabledFeatures = optimizelyClient.getEnabledFeatures("user_1", userAttributes);

* Introduces Feature Variables to configure or parameterize your feature. There are four variable types: `Integer`, `String`, `Double`, `Boolean`.
String stringVariable = optimizelyClient.getFeatureVariableString("my_feature_key", "string_variable_key", "user_1");
Integer integerVariable = optimizelyClient.getFeatureVariableInteger("my_feature_key", "integer_variable_key", "user_1");
Double doubleVariable = optimizelyClient.getFeatureVariableDouble("my_feature_key", "double_variable_key", "user_1");
Boolean booleanVariable = optimizelyClient.getFeatureVariableBoolean("my_feature_key", "boolean_variable_key", "user_1");

### Breaking changes
* The `track` API with revenue value as a stand-alone parameter has been removed. The revenue value should be passed in as an entry of the event tags map. The key for the revenue tag is `revenue` and will be treated by Optimizely as the key for analyzing revenue data in results.
Map eventTags = new HashMap();

// reserved "revenue" tag
eventTags.put("revenue", 6432);

optimizelyClient.track("event_key", "user_id", userAttributes, eventTags);

* Live variable accessor methods have been removed and have been replaced with the feature variable methods mentioned above. Feature variables are scoped to a feature so you must supply the feature key in addition to the variable key to access them.

- `getVariableBoolean` now becomes `getFeatureVariableBoolean`
- `getVariableString` now becomes `getFeatureVariableString`
- `getVariableInteger` now becomes `getFeatureVariableInteger`
- `getVariableFloat` now becomes `getFeatureVariableDouble`

* We have removed deprecated classes with the `NotificationBroadcaster` in favor of the new API with the `NotificationCenter`. We have streamlined the API so that it is easily usable with Java Lambdas in *Java 1.8+*. We have also added some convenience methods to add these listeners. Finally, some of the API names have changed slightly (e.g. `clearAllNotifications()` is now `clearAllNotificationListeners()`)

### Bug Fixes
* Fix for the following issue:
Our github issue is [here](
The JobWorkService was probably destroyed but we didn't cancel the
processor. It causes an exception in dequeueWork in our JobWorkService.
We wrapped the dequeueWork with a try/catch and are also now cancelling the background task in onDestroy.

* Fix for possible error when loading logger via dagger (fall back logger provided).

* Load UserProfileService on synchronous start. Also, cleanup UserProfileService cache in the background thread by removing experiments that are no longer in the datafile.