Fix/admin

[Aurelsicoko]

This PR introduces a brand new way to contribute to Strapi. The development workflow has never been easier. You can now create development application to easily create new plugins.

Setup Strapi on your computer:

git clone git@github.com:strapi/strapi.git
cd strapi && npm run setup

Generate a new development project and run it:

strapi new myProject --dev
cd myProject && strapi start

Launch the development workflow for the administration panel

cd admin && npm start

Note: You've to be in your app folder myProject/admin to run WebPack from the admin.

[lauriejim]

LGTM