roles/homeassistant: Deploy Home Assistant

This commit introduces a *homeassistant* role that installs and sets up
Home Assistant using `pip`.

roles/homeassistant/templates/homeassistant.httpd.conf.j2

@@ -0,0 +1,13 @@
+ProxyPreserveHost On
+ProxyRequests Off
+
+ProxyPass /api/websocket ws://localhost:8123/api/websocket
+ProxyPassReverse /api/websocket ws://localhost:8123/api/websocket
+ProxyPass / http://localhost:8123/
+ProxyPassReverse / http://localhost:8123/
+
+RewriteEngine on
+RewriteCond %{HTTP:Upgrade} =websocket [NC]
+RewriteRule /(.*)  ws://localhost:8123/$1 [P,L]
+RewriteCond %{HTTP:Upgrade} !=websocket [NC]
+RewriteRule /(.*)  http://localhost:8123/$1 [P,L]