[backend] install apache backend configuration.
Create the debian/ folder for pkg build.
[backend] move requirements' pip to a folder.

Use it as components.
[backend] pip: requirements are now separated by environments and components.

The components are located in requirements/ sub folder of the backend.
They are used to specify which components are to be installed avoiding
duplicated install requirements in pip.
Ignore virtualenvs, wheels caching and pip download cache.
Add production wheels (mandatory dependencies).
Update README. Simplify installation of needed deps to contribute.
Created a main Makefile that handle all common actions.

* Python virtualenv creation
* Dependencies installation
* Installation in debian package
[frontend] use URL used in PROD.
Merge branch 'debian_pkg'

* debian_pkg:
  [frontend] use URL used in PROD.
  Created a main Makefile that handle all common actions.
  Update README. Simplify installation of needed deps to contribute.
  Add production wheels (mandatory dependencies).
  Ignore virtualenvs, wheels caching and pip download cache.
  [backend] pip: requirements are now separated by environments and components.
  [backend] move requirements' pip to a folder.
  Create the debian/ folder for pkg build.
  [backend] install apache backend configuration.