snf_django: Use wraps in transaction decorator
This is to preserve name of called function.
Do not log in transaction decorator
Add missing init for snf_django.lib.db package
Move transaction.py to snf_django package
snf_django: Add missing import for IntDecimalField
Needed for formfield() method.
Move intdecimalfield.py to snf_django package
Rename it to fields.py and update all migrations that reference the field.
Move managers.py to snf_django package