Initial UserSession class
Extract ForTest mock class to shared context.
Add UserSession persistence specs.
Add UserSession persistance (and fix specs)
Adding Revision::Session
Basic revision "loading" specs written.
Sequel::Revision::Persistor.bulk_load in progress

Loading works but we need a revision object
(to be able to load "deleted" object)
Add Revision::ResourceState

This allow to get some information on an object revision as well
as managing deleted object.
Specs relative to association in Revision works
Fix mix up between :internal_id and :id.
Merge pull request #232 from maxigit/63538006_desing_and_implement_access_to_revision_tables

63538006 desing and implement access to revision tables