Fix NULL-values in max_batch for jobtypes
Create user on job submit if unknown

Auto-created users will have no passwords and won't be able to log in.
Support max_batch == None when creating jobtype
Fix jobtype PUT with max_batch == None
Change "== None" to "is None"
Make user autocreate configurable
Log user autocreation
Allow sorting jobs by user
Take username directly from query result

This saves us one additional query per job
Allow filtering jobs by user
Fix displaying chevron for asc sorting
Fix retaining no_user on changing sorting
Merge pull request #247 from guidow/nulls_in_max_batch_fixes

Fix NULL-values in max_batch for jobtypes
Merge pull request #253 from guidow/sort_filter_by_username

Sort / filter by username
Merge pull request #248 from guidow/autocreate_user

Create user on job submit if unknown