Reorganize file structure

[Ligerx]

After reading up on a bunch more examples, it makes a lot of sense to organize things by module basically. Every page/feature gets its own folder, no more separating related code into separate folders. eg. there's no reason for pages, containers, and components to be separated.

Keeping redux separate still does seem to make sense though. Technically it's all global state, but there are some that are explicitly global (eg. loading, error) and some are shared state between multiple pages.

I'm also not sold on the name features yet.. features, modules, pages, etc

https://github.com/markerikson/react-redux-links/blob/master/project-structure.md

features/
    library/
        index.js
        LibraryFilter.js
        LibraryHeader.js
        ...
    extensions/
        index.js
        ExtensionButton.js
        ExtensionListItem.js
        ...
redux/
    ...
types/
    ...