task/ta-npe-002-04 -- comms module can SMS

nparcel/comms.py
* factored out send_sms() and get_return_date() methods into
  nparcel/comm.py
task/ta-npe-002-05 -- comms module can email

nparcel/comms.py
nparcel/reminder.py
* factored out send_email() method into nparcel/comm.py