Restful API for orders

[KiOui]

Added a Restful API for orders application.

Added the following:

• API views for listing, creating, retrieving and updating Shift objects
• API views for listing, creating, retrieving, updating and destroying Order objects
• API views for listing Product objects
• API views for the features available on the Shift admin screen
• Serializers for all the above methods
• VueJS to easily manage the state of the HTML document in the browser
• A CustomAutoSchema to make adjustments to the provided AutoSchema
• SwaggerUI

Removed the following:

• All views that we were using to provide API-like features that are now implemented in the API
• A couple of templates that are now included in bigger ones to optimize the VueJS and API implementation

To test you can visit /api/docs.

Closes #125
Closes #101

[JobDoesburg]

How does authentication work?

[JobDoesburg]

• We still need to style swagger UI with some TOSTI styling
• In my opinion the API should accept POST to /orders instead of POST to /cart-order or /orders/add
• We should add / improve documentation to the schema

[KiOui]

• In my opinion the API should accept POST to /orders instead of POST to /cart-order or /orders/add

The /cart-order endpoint will still be necessary, I'll try to add the POST to the /orders endpoint.

[KiOui]

We also need to implement token support for the authenticator

[JobDoesburg]

This can be formulated better

[KiOui]

What do you mean?

[KiOui]

As stated here, there is no easy way to implement manual schema adjustments to AutoSchema of OpenAPI for now, so we have to write our own.

[JobDoesburg]

Ja opzicht nice, we moeten alleen ff een issue openen om wat uitgebreidere documentatie hier toe te voegen en OAuth scopes toe te voegen.