Extends management user and group structure (#1268)

* extends user and group structure by introducing fields for issued and integration references

* Add integration checks to group management to prevent groups added by integration.

* Add integration checks to user management to prevent deleting user added by integration.

* Fix broken user update tests

* Initialize all user fields for testing

* Change a serializer option to embedded for IntegrationReference in user and group models

* Add issued field to user api response

* Add IntegrationReference to Group in update groups handler

* Set the default issued field for users in file store

management/server/http/groups_handler.go

@@ -107,10 +107,11 @@ func (h *GroupsHandler) UpdateGroup(w http.ResponseWriter, r *http.Request) {
 		peers = *req.Peers
 	}
 	group := server.Group{
-		ID:     groupID,
-		Name:   req.Name,
-		Peers:  peers,
-		Issued: eg.Issued,
+		ID:                   groupID,
+		Name:                 req.Name,
+		Peers:                peers,
+		Issued:               eg.Issued,
+		IntegrationReference: eg.IntegrationReference,
 	}
 
 	if err := h.accountManager.SaveGroup(account.Id, user.Id, &group); err != nil {