ipaserver role by default tries to configure firewalld but it didn't
check if firewalld related packages were installed.
Similar to DNS and trust to AD features, install firewalld-related
packages before trying to configure firewalld.
Additionally, enable and start firewalld.service because otherwise
firewall-cmd cannot communicate with firewalld itself (it is not
starting on demand).
If and administrator considers not to use firewalld, a default for
ipaserver_setup_firewalld variable has to be set to 'no'.
Fixes: https://github.com/freeipa/ansible-freeipa/issues/116
A new Fedora-27 ditribution specific file has been added. Additionally
ipaserver_packages_adtrust has been updated in all files to contain
[free]ipa-server-trust-ad.