Integration Test for RPC nodes

[JamesSmartCell]

Write a new integration test which ensures the fallback RPC nodes are working correctly.

Test should:

1. Select all networks both mainnet and testnet
2. open the network status page (Select Active Networks -> 'Node' menu item

There should be no red unhappy faces in the list.

Note that by default, the integration tests are using the Fallback RPC nodes (from EthereumNetworkBase), so no action there is required.