Module should be optionally compatible with jpopelka/firewalld

[tykeal]

EL7 systems default to firewalld for the firewalling. The jpopelka/firewalld module is available directly in the EPEL repositories as a package install and is currently the best firewalld module avaialable (maybe puppetlabs will fix their current firewall module to be firewalld compatible too, who knows)

At present the module only supports puppetlabs/firewall it should have the ability to be compatible with jpopelka/firewalld as well for future use.