[CORD-1530]
Make config file directory creation using become an optional step
Cleanup various incongruities in defaults

Change-Id: I6fb77ab1ccdf08a18468adbc59474f94d603fc11
diff --git a/roles/apt-cacher-ng/defaults/main.yml b/roles/apt-cacher-ng/defaults/main.yml
index ec5a1e1..d7f6698 100644
--- a/roles/apt-cacher-ng/defaults/main.yml
+++ b/roles/apt-cacher-ng/defaults/main.yml
@@ -6,6 +6,7 @@
 
 apt_ssl_sites:
   - apt.dockerproject.org
+  - download.docker.com
   - butler.opencloud.cs.arizona.edu
   - deb.nodesource.com
   - artifacts.elastic.co