Added nginx repo key for mainline

nginx/ng/install.sls

@@ -24,13 +24,14 @@ nginx_ppa_repo:
     - humanname: nginx-ppa-{{ grains['oscodename'] }}
     {%- if nginx.ppa_version == 'mainline' %}
     - name: deb http://nginx.org/packages/mainline/ubuntu/ {{ grains['oscodename'] }} nginx
+    - key_url: http://nginx.org/keys/nginx_signing.key
     {%- else %}
     - name: deb http://ppa.launchpad.net/nginx/stable/ubuntu {{ grains['oscodename'] }} main
+    - keyid: C300EE8C
+    - keyserver: keyserver.ubuntu.com
     {%- endif %}
     - file: /etc/apt/sources.list.d/nginx-{{ nginx.ppa_version }}-{{ grains['oscodename'] }}.list
     - dist: {{ grains['oscodename'] }}
-    - keyid: C300EE8C
-    - keyserver: keyserver.ubuntu.com
     - require_in:
       - pkg: nginx_install
     - watch_in: