Stop the product repository knowing too much

[dmanners]

Description

I have removed the knowledge to the Moltin SDK array format from the Product Repository and into the Moltin bridge.

Motivation and context

This fixes https://github.com/KickAssCommerce/KickAssCommerce/issues/10 and also will help us when building more bridges to other api based commerce systems.

How has this been tested?

The frontend is working still!

Screenshots (if appropriate)

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests and code style pass.

• [X] I have read the CONTRIBUTING document.
• [X] My pull request addresses exactly one patch/feature.
• [X] I have created a branch for this patch/feature.
• [X] Each individual commit in the pull request is meaningful.
• [X] I have added tests to cover my changes. - Well the test failed when I made half the change and works now I made the other half.
• [X] If my change requires a change to the documentation, I have updated it accordingly.

If you're unsure about any of these, don't hesitate to ask. We're here to help!