nextcloud: Deploy Nextcloud w/ Apache+PHP-FPM

The *nextcloud* role installs Nextcloud from the specified release
archive, downloading it to the control machine first if necessary, and
configures Apache and PHP-FPM to serve it.

The `nextcloud.yml` playbook uses the *cert* role to install the X.509
certificate for the Nextcloud server, sets up Apache HTTPD with the
*apache* role, and installs Nextcloud using the *nextcloud* role.

The host *cloud0.pyrocufflink.blue* is the Nextcloud server for
Pyrocufflink.

roles/nextcloud/templates/nextcloud.httpd.conf.j2

@@ -0,0 +1,16 @@
+RewriteEngine On
+RewriteCond %{HTTPS} !on
+RewriteRule /.* https://%{SERVER_NAME}$0
+
+Header always set \
+	Strict-Transport-Security "max-age=63072000; includeSubDomains"
+
+<Directory /var/www/html>
+Require all granted
+AllowOverride All
+Options FollowSymLinks MultiViews
+
+<IfModule mod_dav.c>
+Dav off
+</IfModule>
+</Directory>