adding ability to enable/disable https apt repositories

apt-cacher/ng/files/client.conf

-{% from "apt-cacher/ng/map.jinja" import apt_cacher_ng with context %}
+{% from "apt-cacher/ng/map.jinja" import apt_cacher_ng with context -%}
 Acquire::http::Proxy "http://{{ apt_cacher_ng.server_address }}:{{ apt_cacher_ng.server_port }}";
+Acquire::http::Proxy "{{ apt_cacher_ng.https_proxy_enabled }}";

apt-cacher/ng/map.jinja

         'credentials': '/etc/apt-cacher-ng/security.conf',
         'client_config': '/etc/apt/apt.conf.d/80proxy',
         'admin_account': 'root',
-        'admin_passwd': 'admin'
+        'admin_passwd': 'admin',
+        'https_proxy_enabled': 'false'
     },
 }, merge=salt['pillar.get']('apt_cacher_ng')) %}