Add Requires on puppet-resource_api

It's needed since the merge of [1]

[1] puppetlabs/puppetlabs-firewall#1145

Change-Id: If156134ecf968b98578a57dbe14030a1a8c93174

Author: joelcapitao

puppet-firewall.spec

@@ -19,6 +19,7 @@ Source0:        https://github.com/puppetlabs/%{upstream_name}/archive/%{commit}
 BuildArch:      noarch
 
 Requires:       puppet >= 2.7.0
+Requires:       rubygem(puppet-resource_api) >= 1.8.18
 
 %description
 Manages Firewalls such as iptables