SELinux: Support for SELinux on RedHat platforms

Enable support for SELinux on RedHat platforms. The resource
SELinux will be activated before the installation of openstack
takes place.
Delete .fixtures.yml files and use librarian-puppet-simple

Using librarian-puppet-simple to read Puppetfile for your rspec-puppet
fixtures.
Merge pull request #693 from enovance/support_selinux

Support for SELinux on RedHat platforms
Merge pull request #724 from enovance/delete-fixtures-file

Delete .fixtures.yml files and use librarian-puppet-simple
Advanced Firewalling feature

This patch enables Firewalling in this Puppet modules in a flexible way.

* Enable firewalling optionnaly (disabled by default).
* Enable 'pre' firewalling with defaults rules.
* Enable 'post' firewalling with DROP rule, with a debug option to
  disable it.
* Enable default rules for all services (OpenStack, etc).
* Ability to add custom firewall rules with Hiera
* Update puppetlabs-firewall refs
* Refactorize unit-tests