Adding support for non-vagrant/persistant servers.

Adding modified agent.pp/central_server.pp/ejabberd.cfg template for non-vagrant use. 
Init.pp was modified so the packages are mostly distro specific and the use of the epel class can be disabled.

Example use case:
class { 'archipel':
  include_pkg_repos => false
}
class { 'archipel::central_server_nonvagrant':}
class { 'archipel::agent_nonvagrant':}

Tested with https://github.com/michael-leroy/puppet-ejabberd, and should work with lboynton/puppet-ejabberd.