Add postfix module and dependencies

Author: ekohl

puppet/Puppetfile

@@ -3,6 +3,7 @@ moduledir 'external_modules'
 mod 'citrin/htpasswd', '1.0.2'
 mod 'claranet/timezone', '2.0.1'
 mod 'golja/gnupg', '1.2.3'
+mod 'puppet/alternatives', '5.1.0'
 mod 'puppet/archive', '7.1.0'
 mod 'puppet/augeasproviders_core', '4.1.0'
 mod 'puppet/augeasproviders_mounttab', '4.0.0'
@@ -16,6 +17,7 @@ mod 'puppet/letsencrypt', '11.0.0'
 mod 'puppet/mosquitto', '2.0.0'
 mod 'puppet/nodejs', '10.0.0'
 mod 'puppet/pbuilder', '2.0.0'
+mod 'puppet/postfix', '4.4.0'
 mod 'puppet/redis', '9.3.0'
 mod 'puppet/rvm', '3.0.0'
 mod 'puppet/selinux', '4.1.0'