Sync salsa information in signon housekeeping run

Since we use salsa username (and possibly soon profile image and links) we need a housekeeping task to keep the information up to date if the user does not login often.

Do this in a signon housekeeping run, so it also works for nm.debian.org

Edited May 04, 2020 by Enrico Zini

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information