added config for proxy on salt minion

salt/files/minion.conf

@@ -59,6 +59,11 @@ mine_interval: {{ minion.mine.get('interval', 30) }}
 
 log_level: {{ minion.log.level }}
 
+{%- if minion.proxy is defined %}
+proxy_host: {{ minion.proxy.host }}
+proxy_port: {{ minion.proxy.port }}
+{%- endif %}
+
 {%- if minion.sentry is defined %}
 sentry_handler:
 {% for server in minion.sentry.servers %}