Users should not be able to see blockchain payment routes if they are not available

[lullis]

In the case the hub20 instance has lost connection to its ethereum node client, or if the client is out of sync, it should notify the user that the payment route is not available.

• Vue store needs to handle websocket messages that indicate ethereum node is not available
• Vue store needs to handle websocket messages that indicate that ethereum node is reconnected
• List of blockchain routes should only be displayed when ethereum node is available