Added Flask-User project.

As the maintainer of Flask-User, I'd like to add the 'Flask-User' project and the 'lingthio' member to the metaflask repository.

This project has been approved by 'untitaker'. See https://github.com/mitsuhiko/flask/issues/990.

Thank you.
And remove this file. If you want, you can symlink my file into this directory instead, but it's not required.