[router] Do not execute if Nomad is down

[rhlsthrm]

Check Nomad SDK:

If you run 'checkHomes' on the SDK and provide it a list of networks, then you can access 'blacklist' value which is a set of Failed homes

[alexwhte]

@rhlsthrm Do we need error handling for this in Connext Bridge UI?

edit: nvm, commented in master #990

[rhlsthrm]

@rhlsthrm Do we need error handling for this in Connext Bridge UI?

edit: nvm, commented in master #990

This needs a matching task in the SDK because the SDK should also implement this functionality.

[base0010]

After looking at the nomad sdk not convinced that checkHomes is going to give us the correct state of if the destination chain is processing nominally. Needs clarification, but a shared utility that keeps track of the latest block hash of a updater committed root. Then we can have simple logic to compare that to block hash of now. If there is a significant n block lag (tbd what this measure exactly should be and if it needs be dynamic) we know the destination chain is down.