New accounts should be created with a set of default groups

[maarten-litmaath]

Currently, a new account is created with no group memberships, which have to be requested or assigned separately.

It would be good if a set of default groups and roles could be configured by the VO admin(s), to be assigned automatically to any new account (any unwanted group for an account can always be removed later).

At the very least, the VO root group should be automatically configured, so that e.g. voms-proxy-init may already work without an extra step for ordinary users.

If at least that last option could be implemented easily, it would be good to have that available very soon, thanks!