[FIX] im_livechat: many2one channel_id of im_session to the right model.

In im_session model, field channel_id was a many2one to im_user, or, obviously, this should be a many2one to im_livechat.channel
Well, obviously, this is a copy/paste error (or distraction, your choice!). This fix should normally not be pushed on a stable branch (like the current one, saas-2), but considering the severity of the problem, and the few changes in database (alter foreign key only), this is acceptable. Why such a big mistake has not been seen earlier ? Do you even test or read back what you write ?

bzr revid: dle@openerp.com-20131204122727-q0ch5j2v8rrli41e

addons/im_livechat/im_livechat.py

@@ -210,5 +210,5 @@ class im_session(osv.osv):
     _inherit = 'im.session'
 
     _columns = {
-        'channel_id': fields.many2one("im.user", "Channel"),
+        'channel_id': fields.many2one("im_livechat.channel", "Channel"),
     }