Model service status inacurate

[themoenen]

Problem
Google Cloud (and possibly other environments) will return a placeholder HTML page while your service is deploying or after it failed deploying. But this placeholder is sent with status code 200, which causes OpenAD to list the service as "Connected" while it's not.

Solution
Instead of:

 if response.status_code == 200:
    ret_status["message"] = "Connected"

We need to do something like:

 if response.status_code == 200:
    try:
        if "ok" in response.json()
            ret_status["message"] = "Connected"
    except Exception:
        ret_status["message"] = "Unavailable"

[themoenen]

Note: the same logic should be applied in other places where we only check for status code and assume connectivity, like get_remote_service_definitions() etc.

response.json() will cause an unintelligable error because the response is returned as text:

Expecting value: line 1 column 1 (char 0)

This is printed on startup, on service status, etc.