GitLab

select_for_update for project and membership

* It should optionally work with user dictionary 
instead of contacting astakos.
* Fix pep8 errors

Change astakos user registration procedure in order to send to quotaholder 0 instead of None (infinite)

Update Astakos API to provider calls for retrieving uuid from the username and vice versa, extend astakos client library (snf-common) and update pithos to use uuids instead of email for account identification

Exceptions regarding limit violations now carry details
as specified in CommissionValueException