task/de07-ta88 -- Refactor the e-mail comms facility to be "prod"
aware (REST Interface)

nparcel/emailerbase.py
* new attribute "hostname" that captures the name of the machine

nparcel/restemailer.py
* RestEmailer() class now inherits from nparcel.Emailer()
* new method check_subject() that checks if current hostname
  matches prod.  If so, subject line is prepended with a special
  TEST ONLY descriptor
* update the create_comms() method signature to include "prod"
  parameter that represents the name of the production instance