date_joined variable is set by auto_add_now, not timezone.now(), that is actual argument, not applied to DateField
previous SignUp class had been inherited User in model class, abnormal DB have been created. It's fixed
.DS_store is excluded in git status list
user model migration 0001
team model and MtoM models migration 0001, 0002
project model migratoin 0001
Merge pull request #46 from wikibootup/migration

SignUp class in views.py error fixed, membership class in teams' model error fixed