SMTP authentication support

It will default to no-auth. 
To add SMTP authentication you need to modify smtp_client in system_config to:
"relay": "your_smtp_server",
       "username": "username",
       "password": "password",
       "port": "25",
       "auth": "always"
Merge pull request #5 from remac/patch-1

SMTP authentication support - KAZOO-636