[FIX] http: setup_lang in Safari

When not logged in the webstie on Safari and clicking on "Have a Question? Chat with us",
it creates a mail.channel from get_mail_channel and it also creates a translation.
But with Safari, the accept_languages is set with the value 'fr-fr', and this value was set
in the context as the lang='fr_fr'. So when the translation was created, a bad insert query was
raised in sql because the lang didn't exist in the res.lang table. When a translation is created,
the function _get_languages checked that the language is in the table.
So it was impossible to use the chatter when the user is not logged.

NB: interseting functions to see:

-setup_lang in odoo/http.py
-_dispatch in addons/website/models/ir_http.py
-get_mail_channel in addons/im_livechat/models/im_livechat_channel.py

opw:716519

openerp/http.py

@@ -1357,9 +1357,16 @@ class Root(object):
             httprequest.session.db = db_monodb(httprequest)
 
     def setup_lang(self, httprequest):
-        if not "lang" in httprequest.session.context:
-            lang = httprequest.accept_languages.best or "en_US"
-            lang = babel.core.LOCALE_ALIASES.get(lang, lang).replace('-', '_')
+        if "lang" not in httprequest.session.context:
+            alang = httprequest.accept_languages.best or "en-US"
+            try:
+                code, territory, _, _ = babel.core.parse_locale(alang, sep='-')
+                if territory:
+                    lang = '%s_%s' % (code, territory)
+                else:
+                    lang = babel.code.LOCALE_ALIASES[code]
+            except (ValueError, KeyError):
+                lang = 'en_US'
             httprequest.session.context["lang"] = lang
 
     def get_request(self, httprequest):