Fix httpd::python.

While writing acceptance tests for puppet-httpd we noticed that the
manifest of httpd::python is not working on Ubuntu Trusty.

The httpd::python manifest was using a non-declared
$apache::params::mod_python_package instead of
$httpd::params::mod_python_package

Change-Id: I4db9298aba7da90a017527b2fb29dcd17af28efc
Co-Authored-By: Danilo Ramalho <dramalho@thoughtworks.com>

manifests/python.pp

@@ -18,7 +18,7 @@ class httpd::python {
 
   package { 'apache_python_package':
     ensure => present,
-    name   => $apache::params::mod_python_package,
+    name   => $httpd::params::mod_python_package,
   }
   httpd_mod { 'python': ensure => present, }