chouette-core/spec/models/referential, branch robert-bup

Refs: #4802@0.15h;

2017-11-03T13:49:37+00:00

  CR 2nd part

  - typos
  - unnecessary `class: Referential` removed from referentials_factory
  - regrouping of referential_suite related model specs

Refs: #4802@2h; Replaying former work. To identify spec regression

2017-11-02T06:52:45+00:00

    Step 2: Added validation of reference->workbench->organisation consistency
            Made all specs pass
            Chased bug #4826