Restructure the Ubuntu Getting Started Section.

- This supercedes PR #1770
 - This breaks up the section from one huge installation page into:
   - A new index page.
   - New support grid with commercial and community support options.
   - Move to lifecycle-based pages based on operational tasks.
     - Add support for local deployments via LXD.
       - Added screenshots to images/docs/ubuntu
     - Add backup page.
     - Add decommissioning page.
     - Add a glossary of terms page.
     - Rewritten installation page.
     - Add logging page.
     - Add monitoring page.
     - Add networking page, flannel only for now, calico in progress.
     - Add a scaling page.
     - Add a security page.
     - Add a storage page.
     - Add a troubleshooting page.
     - Add an upgrade page.
     - Add a cluster validation page.
     - Add new ubuntu content to the index page.
       - Add Ubuntu to _data TOC.
     - Add warning about choosing ipv6 with LXD, thanks Ed Baluf.
     - Template-ize all the pages per jaredb's review.

docs/getting-started-guides/ubuntu/security.md

@@ -0,0 +1,33 @@
+---
+Title: Security Considerations
+---
+
+{% capture overview %}
+This page explains the security considerations of a deployed cluster and production recommendations.
+{% endcapture %}
+{% capture prerequisites %}
+This page assumes you have a working Juju deployed cluster.
+{% endcapture %}
+
+By default all connections between every provided node is secured via TLS by easyrsa, including the etcd cluster. 
+
+## Implementation
+
+The TLS and easyrsa implementations use the following [layers](https://jujucharms.com/docs/2.0/developer-layers). 
+
+[layer-tls-client](https://github.com/juju-solutions/layer-tls-client)
+[layer-easyrsa](https://github.com/juju-solutions/layer-easyrsa)
+
+{% capture steps %}
+## Limiting ssh access
+
+By default the administrator can ssh to any deployed node in a cluster. You can mass disable ssh access to the cluster nodes by issuing the following command.
+
+    juju model-config proxy-ssh=true
+
+Note: The Juju controller node will still have open ssh access in your cloud, and will be used as a jump host in this case.
+
+Refer to the [model management](https://jujucharms.com/docs/2.0/models) page in the Juju documentation for instructions on how to manage ssh keys.
+{% endcapture %}
+
+{% include templates/task.md %}