Move SSL certificates from /etc/pki/acmetool-certs to /matrix/ssl

Moving keeps everything in the /matrix directory, so that we
wouldn't contaminate anything else on the system or risk
clashing with something else.

Also retrieving certificates separately for the Riot and Matrix domains,
which should help in multiple ways:

- allows them to be very different (completely separate base domain..)

- allows for Riot to be disabled for the playbook some time later
  and still have the code not break

roles/matrix-server/tasks/setup_s3fs.yml

@@ -26,7 +26,7 @@
 # Tasks related to getting rid of s3fs (if it was previously enabled)
 #
 
-- name: Check existance of matrix-s3fs service
+- name: Check existence of matrix-s3fs service
   stat: path="/etc/systemd/system/matrix-s3fs.service"
   register: matrix_s3fs_service_stat
 
@@ -51,4 +51,4 @@
   docker_image:
     name: "{{ docker_s3fs_image }}"
     state: absent
-  when: "not matrix_s3_media_store_enabled"
+  when: "not matrix_s3_media_store_enabled"