Add API Version 2 support

[zgrguric]

Summary

XRPL is now supporting API version 2 for WS and RPC outputs. Also add this functionality to xahaud.

Motivation

To migrate existing tools to new API version which will work on both networks.

[tequdev]

API version 2 was released with 2.0.0 of rippled, but at this time xahaud is following rippled up to 1.11.0.

Until xahaud supports API Version2, you can make WS/RPC requests on the same interface by using API verison1 with rippled.

[zgrguric]

That is fine, as long it is planned.