allow all python versions

Fixes issue voxpupuli#448, "Impossible to use version number in Ubuntu 16.04"

1) It does not make sense to restrict the allowed python versions per
distribution. Newer distribution releases add new python versions and
you can add repositories containing backports.
2) The List was outdated.

manifests/init.pp

@@ -62,8 +62,9 @@
   }
 
   $allowed_versions = concat(['system', 'pypy'], $valid_versions)
-  unless $version =~ Enum[$allowed_versions] {
-    fail("version needs to be within${allowed_versions}")
+  unless $version =~ Pattern[/\A(python)?[0-9](\.[0-9])+/,
+        /\Apypy\Z/, /\Asystem\Z/] {
+    fail("version needs to be pypy, system or a version string like '3.5' or 'python3.5)")
   }
 
   # Module compatibility check

manifests/install.pp

@@ -9,7 +9,8 @@
   $python = $::python::version ? {
     'system' => 'python',
     'pypy'   => 'pypy',
-    default  => "${python::version}", # lint:ignore:only_variable_string
+    /\A(python)?([0-9](\.[0-9])+)/ => "python${1}",
+    default  => "python${python::version}",
   }
 
   $pythondev = $::osfamily ? {

manifests/params.pp

@@ -10,12 +10,7 @@
   $gunicorn               = 'absent'
   $manage_gunicorn        = true
   $provider               = undef
-  $valid_versions = $::osfamily ? {
-    'RedHat' => ['3','27','33'],
-    'Debian' => ['3', '3.3', '2.7'],
-    'Suse'   => [],
-    'Gentoo' => ['2.7', '3.3', '3.4', '3.5']
-  }
+  $valid_versions         = undef
 
   if $::osfamily == 'RedHat' {
     if $::operatingsystem != 'Fedora' {