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.

nextcloud.yml

@@ -0,0 +1,11 @@
+- hosts: nextcloud
+  vars_files:
+  - vault/nextcloud
+  roles:
+  - role: cert
+    cert_src: lego/_.pyrocufflink.net.crt
+    cert_dest: '{{ apache_ssl_certificate }}'
+    cert_key_src: lego/_.pyrocufflink.net.key
+    cert_key_dest: '{{ apache_ssl_certificate_key }}'
+  - apache
+  - nextcloud