Corrected auth.BaseUser shallow models (+3 squashed commits)
Squashed commits:
[0455180] Added baseuser object to shallow models
[c516b65] Changed user reference in migration files
[74bc5f0] Made the related_name for models.Customer configurable by setting.

Changed user reference in migration files

Added baseuser object to shallow models

Corrected auth.BaseUser shallow models
Merge pull request #5 from FoundersAS/feature/configurable_related_name

Implemented configurable related_name for DJStripe Customer model