[FEATURE] Create test for db auction

# Changelog:
Add a part of test (test of DB auction)
# Motivation:
I developed an one auction 10 years ago. I want to share the experience.
# Usage guide:
Code for creating the table can be used in node/setup_db.py
# Roadmap:
* test_auction.py (DB,node/auction,FrontEnd api,protocol, etc.),
* DB(node/setup_db.py), 
* node/auction.py, 
* etc.

welcome to OpenBazaar, last time I checked this project was for users who precisely couldn't receive payments because they don't have banking nor merchant services, I don't see a single file here doing paypal integration nor has anyone mentioned such a feature since the project started, or have they?