* Notification Listener Changes

* example of using notification center.

* removed type from addNotification overloads

* updated to match the design doc

* asserts in send notifications

* merge fixes

* test cases for NotificationCenter

* removed SwiftNotifyTest

* property for OPTLYNotificationCenter in OPTLYClient

* fix - file reference

* Track tests added
Copyright updated

* convert if to case statement