Fix configuration error 'No value for persistToken' by using optBoolean()
instead of getBoolean(). The getBoolean() method throws JSONException
when the key doesn't exist, while optBoolean() returns the default value
(false) safely.
This allows configureNativeFetcher() to work when persistToken is not
provided in the options, which is the expected default behavior (tokens
are not persisted by default for security).
973af9b688