Tie the store type configuration entity type to the store content entity type as the bundle provider.
Use the ConfigEntityBundleBase class for the store type entity class.
Update CommerceStoreType.php

Missing use Drupal\Core\Config\Entity\ConfigEntityBundleBase;
Merge pull request #3 from scotthooker/patch-1

Update CommerceStoreType.php
middle of working on product types
Merge branch '8.x-2.x' of https://github.com/commerceguys/commerce into 8.x-2.x
product types working