Add support for setting user expire

pillar.example

@@ -9,6 +9,7 @@ users:
     password: $6$w.............
     home: /custom/buser
     createhome: True
+    expire: 16426
     sudouser: True
     sudo_rules:
       - ALL=(root) /usr/bin/find

users/init.sls

@@ -58,6 +58,9 @@
     {% if not user.get('createhome', True) %}
     - createhome: False
     {% endif %}
+    {% if 'expire' in user -%}
+    - expire: {{ user['expire'] }}
+    {% endif -%}
     - remove_groups: {{ user.get('remove_groups', 'False') }}
     - groups:
       - {{ user_group }}