Added auth field to config so that emails are harder to track to sender

Added error handling to identify:
  - errors creating the mail headers
  - errors processing JSON input
  - errors in the mailer configuration
Added fromaddr to mass mailer JSON interface so emails can be sent from
any address without restart.

Removed fromaddr entry from config.yaml.
Merge pull request #849 from geefunkmasterpro/master

Enhancements to Mass Mailer