implement quartermaster APIs

[matthiasbalke]

implement the following json APIs using mocked data:

• api/dashboards - GET - fetch all configured dashboard ids
• api/dashboards/{dashboardId} - GET - fetch the specified dashboard including all widgets configurations for this dashboard
• api/widgets/{widgetId} - GET - fetch widget config for specified widget
• api/widgets/{widgetId} - POST - create a widget
• api/widgets/{widgetId}/data - GET - fetch the current widget data for specified widget

example json to create a widget:

{
  "title" : "myUrlWidget",
  "sourceConfigs" : [
    {
      "id" : "urlSource",
      "type" : "urlSource",
      "interval" : 1000,
      "configData" :
        {
          "url" : "https://echo.getpostman.com/get?test=123"
        }
     }
  ]
}

Widget IDs are globally unique