Begin vendor/product model join tests
Change tested model name to VendorProduct
Add __unicode__ messages to models, add to tests
Revert "Add __unicode__ messages to models, add to tests"

This reverts commit c232738a9ca56ab8b362b9c59792c72f5a65160d.
Update and move VendorProduct test
Correct field types of vendor and products many-to-manys
Write vendor/product join model
Merge branch 'develop' into HEAD
Add docstring for VendorProduct model
Write VendorProduct model