sendmail - Introduce postfix_user_sendmail_privs

The postfix_user_sendmail_privs interface is used to add the proper set
of permissions to the (user|system)_sendmail_t domains.
Fix postfix - make postfix_t launchable from init
Fix postfix - enable output on terminals for debugging and troubleshooting
Mail Infrastructure Policy

The mail infrastructure policy uses the common mail infrastructure
terminology for its attributes, and provides a common interface for mail
related infrastructure to use SELinux.
Create mta wrapper

Also temporarily rename the mta policy (instead of removing it) so we
can consult it during development of the new mail infrastructure policy.
Fix postfix - postfix_local_t is delivery agent
Mark sysadm as a mail_role capable userdomain