Removed `configuration_failed` state.

There is no longer `configuration_failed` state for apps in the API.
Also moved duplicated message to helper method (suggested here:
https://github.com/shellycloud/shelly/pull/102/files#r6071739).
Do not show `shelly deploys show last` instruction

if last deployment was made by admin and was failed.

[#55546492]
Merge pull request #103 from shellycloud/55546492-wrong-status-message-when-admin-maintenance-fails

Do not show `shelly deploys..` instruction if app is in maintenance