Background events
Background events

Summary:
`this.client.subscribe` was used to listen for navigation events. This means, navigation events are not collected while the plugin is in background.
In this diff, this is changed to a persistedStateReducer, so the events are collected with the plugin not active.

Reviewed By: jknoxville

Differential Revision: D17419668

fbshipit-source-id: 88d9476cb7461ff6774d42a992d32b4c8948ac86

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