[FIX] Translate model in chatter widget (7.0 lp:1262000)

Retry of #20 using recommendations of @fpodoo ; port of [lp:1262000](https://bugs.launchpad.net/openobject-addons/+bug/1262000)

This patch finds the translated name of the model for which the chatter is posting and uses that instead of the _description.

The advantage of this over the #20 implementation is that the `ir.model` name field is already exported in traductions and not .po files have to be updated.

Description
--------------

Chatter messages are not fully translated

How to reproduce
-----------------------

In another language, create and object which has a chatter

Expected output
---------------------

Chatter has the object name translated

E.g:

> Usagé créé(e)

Actual output
----------------

Chatter translates all but the name

E.g.

> User créé(e)

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>