CodeIgniter4.0.0-dev Reaches Milestone 1

I have updated the readme in the repository, and added an index.html page to the project root, explaining the slightly different project structure.

I strongly encourage you to build the user guide, and to read it.

@wolfgang1983 See concepts/autoloader in the user guide
@wolfgang1983 bitnami.com has PHP7 WAMP stacks you can deploy.
@wolfgang1983, @parthpabari See concepts/structure for a detaled explanation of the new folder structure