Write unit tests for Vendor model
Update Vendor model with another test

Made the 'only contain what I want' test, and made the other tests
actually work.
Add word 'test' so test will run
Create tests subdirectory, update tests for compactness
Fix Pep8 issues with model tests
Test created/modified fields; get rid of extraneous image tests
Change u'id' from unicode to ascii string
Created a test for the product model

refs #16431
Use ForeignKey for foreign keys and NullBooleanField in tests
Create Product model
Changed link field from TextField to URLField

refs #16431
Merge branch 'feature/16431' of github.com:osu-cass/whats-fresh-api into feature/16431

Conflicts:
	project_fish/whats_fresh/tests/test_products_model.py
Updated link field from TextField to URL field

refs #16431

Updated the link field in the product model to match the test.
Create Preparation model unit tests

Test if all fields are of proper type, and that only the expected fields
exist.
Make preparation model tests actually work
Rewrite preparation model tests based on Vendor model tests

Move into tests folder and use a dictionary to track test
Change unicode test string to ascii
Create Preparation model
Created test for the Product Preparation model

refs #16581
Added product preparation model to models.py

refs #16581