Develop Registration model

[viktor-yakubiv]

The registration model is a part of the DataProvider model. It's a simple creation of a data provider on the API level.

On the other hand, the registration form (component) should store its state and maybe share it across various pages (discussable).

It can be based on MobX but any other framework or pure JS implementation is an option.

Let's discuss it all.

[viktor-yakubiv]

As a part of this, I would like to reference a comment from #1:

[Registration form's] render method should stay pure. The state management should be placed in another component.