Feat/371 view only user implementation using user_permissions (#381)

* https://github.com/jambonz/jambonz-api-server/issues/371

Implemented view_only permission feature

* calling prepare-permissions in create-test-db.js

* check if there is only 1 permission and if it is VIEW_ONLY then consider user as read-only user

* setting is_view_only flag for view user by userid

lib/utils/errors.js

@@ -27,11 +27,17 @@ class DbErrorForbidden extends DbError {
     super(msg);
   }
 }
+class UserPermissionError extends Error {
+  constructor(msg) {
+    super(msg);
+  }
+}
 
 module.exports = {
   BadRequestError,
   DbError,
   DbErrorBadRequest,
   DbErrorUnprocessableRequest,
-  DbErrorForbidden
+  DbErrorForbidden,
+  UserPermissionError
 };