[FIX] Bug Import. TODO: Import crawler should use same function as in constants (duplicata of code).

(importing the graph advances in my branch)

[FIX] project view progressbars (2/2): the check time intervals were returned from the wrong django view function

This reverts commit d9d93ae0, reversing
changes made to 4ef20306.

- Graphes asynchrones testés en mode prod
- Documentation, README amélioré
- cosmetics: aération du code (en particulier bridgeness...)
- factorisation et meilleur positionnement de la fonction compute_graph

 Modifications qui seront validées :
	modifié :         README.md
	modifié :         bridgeness.py
	modifié :         cooccurrences.py
	modifié :         graph.py

[GRAPH] Now graph as json is saved according to its distance as key (needs to add bridgeness parameter as key).

[FIX] project view progressbars: add nDocs update and fix loop closure if several corpora are active