Set pyvers in defaults

This allows openstacklib::defaults to be inherited by each component
module avoiding duplicating the logic currently required when setting
this for the various base distrobutions.

Change-Id: I84b767921d151a61429b2c89e6372c4b447f0d7d

manifests/defaults.pp

@@ -12,4 +12,16 @@ class openstacklib::defaults {
     warning('OpenStack modules support for Puppet 4 is deprecated \
 and will be officially unsupported in the T release')
   }
+
+  if ($::os['family'] == 'Debian') {
+    $pyvers = '3'
+    $pyver3 = '3'
+  } elsif ($::os['name'] == 'Fedora') or
+          ($::os['family'] == 'RedHat' and Integer.new($::os['release']['major']) > 7) {
+    $pyvers = '3'
+    $pyver3 = '3.6'
+  } else {
+    $pyvers = ''
+    $pyver3 = '2.7'
+  }
 }