Basic WSGI application.
.travis.yml: Add dependency.
Add support for answering to valid requests.
Make router able to call modules.
Send the payload to modules.
Improve tests coverage.
Remove code duplication in tests.
Add support for modules which are unreachable.
Add how to install/use to the README.
Add dependencies to setup.py.
Remove dependency_links as it seems to be ignored.

I also added ppp_datamodel to Pypi so it is not needed anymore.
Merge pull request #1 from ProjetPP/base

Write a basic working router.