[FIX] Add context propagation for m2m list view

Fix bug https://bugs.launchpad.net/openerp-web/+bug/1279885 :
    Many2many fields in Tree views will not get translated.
    If you check the context for a name_get of a m2m field, it is passed as
    None.

Add context propagation to m2m fields in list views.
Fix translation issues when viewing a a many2many field in a Tree view.
Merge pull request #17 from savoirfairelinux/7.0-m2m-context

[FIX] view_list: Add context propagation for m2m list view

If the _rec_name field of a model is translatable, the value was not translated when displayed in a list view through a many2many field (e.g. server_action_ids on base.action.rule).