StratisCore UI should not be able to login if SignalR connection is not made

[ianadavies]

A minor one,

But we should probably try and make a SignalR connection on the login page and not allow users to login if no SignalR Connection is made, and show appropriate error message.

SignalR is now a dependency and if we start the full node without it enabled we get strange behaviour. See Image below

[dangershony]

SignalR is now a dependency

Hmm why make SignalR a dependency?
Is that intentional? is it not avoidable?

[ianadavies]

We just use SignalR now for all real-time wallet updates as it's more efficient and means we don't constantly poll the FullNode. We did consider making it backwards compatible but as the FullNode is shipped with the Wallet we decided it was unnecessary work.