[FIX] ir.mail_server: SMTP user and pass should be passed as bytes to login()

Passing a unicode used to work in Python 2.5 but that
changed in 2.6 due to a change in the hmac module.
In any case the various RFCs that describe such
authentication mechanism do specify that UTF-8 encoded
values should be used, so we should be safe coercing
the user and passsword to UTF-8 bytes strings.
And of course it should not change anything for
the ASCII passwords out there anyway.

For references, see:
- Zope bug https://bugs.launchpad.net/zope.sendmail/+bug/597143
- Python issue http://bugs.python.org/issue5285
- http://tools.ietf.org/html/draft-ietf-sasl-crammd5-10#section-4

bzr revid: odo@openerp.com-20120312174348-iiqfa2toupn3udr3

openerp/addons/base/ir/ir_mail_server.py

@@ -232,6 +232,11 @@ class ir_mail_server(osv.osv):
 
         if user:
             # Attempt authentication - will raise if AUTH service not supported
+            # The user/password must be converted to bytestrings in order to be usable for
+            # certain hashing schemes, like HMAC.
+            # See also bug #597143 and python issue #5285
+            user = tools.ustr(user).encode('utf-8')
+            password = tools.ustr(password).encode('utf-8') 
             connection.login(user, password)
         return connection