ClusterManager: Implements support of remote clusters.

After this change users will be able to:
* Create cluster and add/remove servers to it
* Install apps on remote cluster
* Move already installed apps between clusters
* Apps running on server being removed will auto-migrate
  to another server from that same cluster

This is achieved by:
* Installing and running minimal version of dodo on remote cluster
* Ingress-nginx is installed automatically on new clusters
* Next to nginx we run VPN client in the same pod, so that
  default cluster can establish secure communication with it
* Multiple reverse proxies are configured to get to the
  remote cluster service from ingress installed on default cluster.

Next steps:
* Support remote clusters in dodo apps (prototype ready)
* Clean up old cluster when moving app to the new one. Currently
  old cluster keeps running app pods even though no ingress can
  reach it anymore.

Change-Id: Iffc908c93416d4126a8e1c2832eae7b659cb8044
diff --git a/core/installer/welcome/appmanager-tmpl/base.html b/core/installer/welcome/appmanager-tmpl/base.html
index 4458485..cb69970 100644
--- a/core/installer/welcome/appmanager-tmpl/base.html
+++ b/core/installer/welcome/appmanager-tmpl/base.html
@@ -18,6 +18,8 @@
                   <li><a href="/installed" class="{{ if (eq .CurrentPage "installed") }}primary{{ end }}">Installed</a></li>
                   <li><a href="/not-installed" class="{{ if (eq .CurrentPage "not-installed") }}primary{{ end }}">Not Installed</a></li>
                   <hr>
+                  <li><a href="/clusters" class="{{ if (eq .CurrentPage "clusters") }}primary{{ end }}">Clusters</a></li>
+				  <hr>
                   {{ block "extra_menu" . }}{{ end }}
                 </ul>
             </nav>
@@ -29,3 +31,16 @@
     <script src="/stat/app-manager.js?v=0.0.11"></script>
 	</body>
 </html>
+
+{{ define "task" }}
+{{ range . }}
+<li aria-busy="{{ eq .Status 1 }}">
+	{{ if eq .Status 3 }}<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="black" d="M21 7L9 19l-5.5-5.5l1.41-1.41L9 16.17L19.59 5.59z"/></svg>{{ end }}{{ .Title }}{{ if .Err }} - {{ .Err.Error }} {{ end }}
+	{{ if .Subtasks }}
+	<ul>
+   		{{ template "task" .Subtasks }}
+	</ul>
+	{{ end }}
+</li>
+{{ end }}
+{{ end }}