NetworkRequestStatsHandler

The library provides a default implementation of this interface, PersistentStatsHandler.

Responsibilities:

1. Allows the client to register/deregister his own listeners, and gives callback to all the registered listeners in case of success or errors responses.

2. The client will be able to get the current network information for a particular request.

3. Gives the network speed based upon the type of current network

4. Calculates the average network speed based upon the request and responses, and saves it to SharedPreferences to retrieve it later. The client can set the maximum number of request after which the size is saved into sharedpref. In future updates, time strategy also will be supported.