To change base quota for a specified user:
  snf-manage user-modify user --set-base-quota resource limit

To import base quota in batch from a file:
  snf-manage astakos-quota --import-base-quota filename

Rename `initial' to `base quota' in command output.
Move code that creates/removes AstakosUserQuota entries in file quotas.py;
sync user to quotaholder after such a change.

Refs #3411