Don't require virtualenv package

Use puppet-python's checks to ensure presence of python packages.
This way we don't create conflicting Package['virtualenv'] entries.

Change-Id: I3435a2527f4712d068c5a3c43728bed6011e1ebd

manifests/install.pp

@@ -19,10 +19,10 @@ class askbot::install (
     ensure => present,
   }
 
-  if !defined(Package['virtualenv']) {
-    package { 'virtualenv':
-      ensure => present,
-    }
+  class { '::python':
+    pip        => true,
+    dev        => true,
+    virtualenv => true,
   }
 
   python::virtualenv { '/usr/askbot-env':
@@ -30,7 +30,6 @@ class askbot::install (
     owner   => 'root',
     group   => 'root',
     timeout => 0,
-    require => Package['virtualenv'],
   }
 
   case $db_provider {