Defining resource name as integer may give unintended access in vantage6

vantage6 is privacy preserving federated learning infrastructure. Prior to version 4.0.0, malicious users may try to get access to resources they are not allowed to see, by creating resources with integers as names. One example where this is a risk, is when users define which users are allowed to run algorithms on their node. This may be defined by username or user id. Now, for example, if user id 13 is allowed to run tasks, and an attacker creates a username with username '13', they would be wrongly allowed to run an algorithm. There may also be other places in the code where such a mixup of resource ID or name leads to issues. Version 4.0.0 contains a patch for this issue. The best solution is to check when resources are created or modified, that the resource name always starts with a character.