Remove dependency with material-ui

[jeromemacias]

What about create abstract components where the render method is not defined ?
So we will be able to use them without material-ui style dependency.

For examaple, Pagination could be extended by MaterialPaginationand so we will be able to create BootstrapPagination which render pagination in Bootstrap style.

We can even imagine a "themification" of the admin.

[fzaninotto]

All the material-ui related stuff is already inside a mui directory, it shouldn't be difficult to make it a standalone component - that's already the long-term goal.

However, before making the installation more complex by asking users to install 2 directories, and before making development more complex by asking developers to synchronize changes on 2 repositories, we'll continue bundling material UI components up to a stable release.

In the meantime, if you want to work on an alternative view (bootstrap?), feel free to submit a PR on this repository.

I'll close the issue as it's already something that we have in mind, but for now, admin-on-rest is material-ui only.

[fzaninotto]

Now that #1543 is merged, it its completely possible to create a new distribution with bootstrap for instance. \o/

[jeromemacias]

Nice job, impressive !