Enable and use salt_api proxy by default

 * Use nginx as proxy
 * Misc: define defaults for
    salt_master_host
    infra_config_address
    reclass_config_master
    jenkins_salt_api_url
 * Pass certs dir for jenkins docker slaves

Related: PROD-27641(PROD:27641)
Related: PROD-30528(PROD:30528)

Change-Id: I5fac90101131a8d8d4fa7857982f18c855e0771c
diff --git a/defaults/init.yml b/defaults/init.yml
index bcee4bf..c90c404 100644
--- a/defaults/init.yml
+++ b/defaults/init.yml
@@ -11,6 +11,7 @@
 - system.defaults.backupninja
 - system.defaults.git
 - system.defaults.glusterfs
+- system.defaults.nginx
 - system.defaults.jenkins
 - system.defaults.maas
 - system.defaults.opencontrail
@@ -55,3 +56,6 @@
     # Cloudwatch api removed from Queens
     openstack_heat_cloudwatch_api_enabled: True
 
+    salt_master_host: '127.0.0.1'
+    infra_config_address: '127.0.0.1'
+    reclass_config_master: '127.0.0.1'