Added #171

and my NSString *clientID fix, which might not be as good as
https://github.com/fullstackreact/react-native-oauth/blob/2f8c8d1483526bbc8a6ca72183c6d11a71538ad3/ios/OAuthManager/OAuthManager.m

Author: SailingSteve

android/src/main/java/io/fullstack/oauth/OAuthManagerModule.java

@@ -401,7 +401,6 @@ private WritableMap accessTokenResponse(
   ) {
     WritableMap resp = Arguments.createMap();
     WritableMap response = Arguments.createMap();
-    Map accessTokenMap = new Gson().fromJson(accessToken.getRawResponse(), Map.class);
 
     Log.d(TAG, "Credential raw response: " + accessToken.getRawResponse());