chore: release 2.1.1 (optimizely#195)

* Fix impression sent from feature experiment variation toggled off. (optimizely#193)

chore: release 2.0.2 (optimizely#194)

* Fix impression sent from feature experiment variation toggled off. (optimizely#193)

Update date (optimizely#190)

prepare for minor bug fix release (optimizely#181)

* prepare for minor bug fix release

* fix hurried changelog entry

refactor so that any java 8 or later can use lambdas for Activate and… (

optimizely#175)

* refactor so that any java 8 or later can use lambdas for Activate and Track listeners.

* make some updates according to mike's comments

* add some unit tests to up code coverage

Add release notes for the 2.0 beta. (optimizely#176)

add changelog

update changelog with beta4 and beta5 notes

rename ActivateNotification to ActivateNotificationListener same with… (

optimizely#166)

* rename ActivateNotification to ActivateNotificationListener same with TrackNotificationListener

* remove unused imports