Add manage_postfix conditional

Allow local MTA management to be disabled for hosts which need a custom
configuration.

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

salt/common/suse.sls

@@ -12,7 +12,9 @@ include:
   - users
   {%- endif %}
   - .ssh
+  {%- if salt['pillar.get']('manage_postfix', True) %}
   - postfix.config
+  {%- endif %}
 
 {#- to-do: move this to some formula or macro -#}
 {%- set osfullname = grains['osfullname'] -%}