Failover
This PR adds failover
support to dhive.
In case the current RPC node hangs-up/freezes/stops, it's going to switch the node and tries again, until failoverThreshold
has been reached (defaults to 3).
This function is optional and only active if the RPC node parameter is an array. (new Client(['api.node', 'api2.node]
instead of a simple string new Client('api.node')
.