Ensure postfix is installed prior to removing sendmail
Ensure postfix is installed prior to removing sendmail

This resolves issue #27. If postfix is present when sendmail is removed, cronie
will not be removed.

bbaassssiiee/RHEL6-STIG,defionscode/RHEL6-STIG,shepdelacreme/RHEL6-STIG,MindPointGroup/RHEL6-STIG,MindPointGroup/RHEL6-STIG,defionscode/RHEL6-STIG,samdoran/ansible-role-rhel6stig,bbaassssiiee/RHEL6-STIG,samdoran/ansible-role-rhel6stig,shepdelacreme/RHEL6-STIG