Add a circuit-breaker

[fstamour]

Description

I lost internet connection for a moment, but local-gitlab kept periodically trying to fetch information from GitLab. And I had slime connected to it, so I had many debugger (automatically) opened in Emacs.

Acceptance Criteria

• When GitLab's domain name cannot be resolved, don't invoke the debugger (e.g. add a handler-case)
• When multiple errors happen one after the other, when making requests to GitLab. The local-gitlab should stop making new requests for a while, only making a request from time to time in order to verify if the system recovered.
• (Optional) Show a message in the WebUI when the service is degraded. (But keep showing the data)
• In the WebUI, show the last update time

[fstamour]

Here, it happened again: