py3: use email.utils module instead of email.Utils...
py3: use email.utils module instead of email.Utils
On py2:
>>> import email
>>> import email.utils as eutil
>>> email.Utils.parseaddr is eutil.parseaddr
True
>>> email.Utils.formatdate is eutil.formatdate
True
email.Utils is not present on Python 3.
Differential Revision:
https://phab.mercurial-scm.org/D2453
