[Python 3]rfc822 module has been removed

Summary:
python 2.7 -3 ./kolab-cli.py -d 9 lm

DeprecationWarning: in 3.x, rfc822 has been removed in favor of the email package

Reviewers: PyKolab Developers, sicherha

Reviewed By: PyKolab Developers, sicherha

Subscribers: sicherha

Differential Revision: https://git.kolab.org/D3457