adapt_framework: react components as adapt components

[oliverfoster]

Subject of the issue

Allow pure react components as adapt components.

Fixes required to current react implementation:

1. img loading=eager won't work on nested react class components as these are passed by instance rather than as a set of react virtual dom nodes
2. should pass props through to the templates, rather than a model and view, as is standard in react, that way the templates can be reused in react native components
3. eslint is not working properly with react templates
4. remove unnecessary functions from reactHelpers, find, close and render
5. rename partials/component.jsx to header.jsx as it can be used for articles and blocks later
6. add image.jsx to centralise the render of graphics and size switching
7. add import references to react and react dom where necessary, remove them from the global scope
8. change view.isReact to view.isJSX as this is more accurate
9. modify the classes function to remove duplicates
10. add a prefixClasses function to allow for classes such as __inner and __header to be prefixed with type and component name more easily