Add indicators for timeliness of information provided by Proxy Service

Current Situation

• Any information about orders and Agents is provided by the Proxy Service.
• If the Proxy Service is not connected to a Controller, then unchanged information is presented. While the information was accurate for a previous point in time, it might not be accurate for the present status of objects. Users cannot easily decide if they are presented current information or outdated information.

Desired Behavior

• The top line of any GUI page is added the indicator "Survey Time: <date-time>" that indicates the last point in time for which information was received from the Proxy Service.
• The Orders widget in the Dashboard view displays order states in various colors if the related Controller is reported being healthy. In case of an unhealthy Controller, all order states are displayed in grey color.