Stop Listening

[esgraham]

Description

As an application user, I'd like to have stop listening code on the iOS and Android, in order to have an event that stops the microphone from listening.

Acceptance Criteria

• Should have a function in the Cognitive Services plugin that implements the stop listening functionality for Android.
• Should have a function in the Cognitive Services plugin that implements the stop listening functionality for iOS.
• README documentation in the plugin should be updated to include changes to the stopListening function and example.