Make sasl install tasks ansible_os_family aware

I still think this file is a hack which should be its own role but for now its
piggy backing on exim. This adds support for installing on Red Hat derived
systems.
Move spamassassin to its own role

It hasn't been pushed yet but the spamassassin component of this role is now
goetzk.spamassassin. Once its been tested it will get pushed to galaxy and
github.