Summary shows artifact servers which are not in use

[gtristan]

I just forgot to put my certs/keys in place before a build.

I saw:

[--:--:--][        ][    main:core activity                 ] WARNING Failed to initialize remote <url>: Failed to load credentials file: /home/tristan/work/project/certs/artifacts.key
[--:--:--][        ][    main:core activity                 ] WARNING Failed to initialize remote <url>:8980: Failed to load credentials file: /home/tristan/work/project/certs/artifacts.key

And then in the summary I had:

    Artifact cache servers
      * <url>:8980
        push: False type: storage instance: None
        loaded from: command line
      * <url>:8982
        push: False type: index instance: None
        loaded from: command line

I think this is incorrect, not sure if we should just omit this data for caches which we were unable to connect to, or perhaps we should just say connected: True or connected: False for clarity.