Add a owner field to the store.

- Move some of the form field definitions to the BaseFieldDefinition on the entity.
- Coding style fixes in the store tests
Adjust forms to reflect core changes, small cleanup.

- Changed submit() to submitForm() on entity delete forms.
- Replaces all occurrences of watchdog() with the logger.
Merge pull request #70 from Jbekker/fix-forms

Adjust forms to reflect core changes, small cleanup.
Merge pull request #69 from Jbekker/add-store-owner

Add a owner field to the store.