Expose data source extended properties (jsonData), to the frontend, Closes #2023

pkg/api/frontendsettings.go

@@ -54,6 +54,10 @@ func getFrontendSettingsMap(c *middleware.Context) (map[string]interface{}, erro
 			defaultDatasource = ds.Name
 		}
 
+		if len(ds.JsonData) > 0 {
+			dsMap["jsonData"] = ds.JsonData
+		}
+
 		if ds.Access == m.DS_ACCESS_DIRECT {
 			if ds.BasicAuth {
 				dsMap["basicAuth"] = util.GetBasicAuthHeader(ds.BasicAuthUser, ds.BasicAuthPassword)