fix(contrib): add --insecure-registry flag for docker 1.3.2

Deis' registry is insecure. Docker is secure-by-default, which means
that we must now whitelist insecure registries on each and every daemon.

Author: Matthew Fisher

contrib/coreos/user-data.example

@@ -53,6 +53,10 @@ write_files:
       function nse() {
         docker exec -it $1 bash
       }
+  - path: /etc/systemd/system/docker.service.d/50-insecure-registry.conf
+    content: |
+        [Service]
+        Environment=DOCKER_OPTS='--insecure-registry="10.0.0.0/8"'
   - path: /run/deis/bin/get_image
     permissions: '0755'
     content: |

docs/contributing/hacking.rst

@@ -103,6 +103,11 @@ Make sure it meets the following requirements:
  #. You can push Docker images from your workstation
  #. Hosts in the cluster can pull images with the same URL
 
+.. note::
+
+    If the development registry is insecure, you'll have to modify contrib/coreos/user-data.example
+    and whitelist your development registry so the daemons can pull your custom components.
+
 Development Workflow
 --------------------