Fix project build

This PR's main goal is to fix the project build. The same changes as in https://github.com/camptocamp/ngeo/pull/58 are made.

To ease development this PR also adds a sample project to the repo. This project was created using the `pyramid_closure` scaffold. When changes are made to the scaffold similar changes should be made to the sample project.

Please review.

Fixes #11.
Fixes #13.