acceptance: do not enable EPEL

EPEL is causing CI failures randomly, because Fedora servers are quite
often down and do not offer EPEL repos in a stable way.

This patch just disables the usage of EPEL which is not needed to
download RabbitMQ.

Change-Id: Ifc04092b924b867063fc5c50960b1600b3fe379d

spec/acceptance/rabbitmq_spec.rb

@@ -10,7 +10,8 @@ describe 'openstacklib class' do
 
       if $::osfamily == 'RedHat' {
         class { '::openstack_extras::repo::redhat::redhat':
-          release => 'kilo',
+          release     => 'kilo',
+          manage_epel => false,
         }
         $package_provider = 'yum'
       } else {