Add helper function ref and browse_ref ir.model.data

Call get_object from ir.model.data registry using common external_id xml syntax
Call get_object_reference from ir.model.data registry using common external_id
xml syntax
PR #5: ir_model_data helpers in Session API

Merge branch 'session_ref' of https://github.com/savoirfairelinux/anybox.recipe.odoo
Update changelog and add Sandy to contributors