Ensure debian-like distributions get the latest version of certbot

- Remove the non-standard Ubuntu 16.04 package and script name (letsencrypt vs certbot)
- Add the EFF-maintained certbot PPA

tasks/install-with-package.yml

@@ -1,4 +1,9 @@
 ---
+- name: Ensure package repo is present
+  apt_repository:
+    repo: ppa:certbot/certbot
+  when: ansible_distribution == "Ubuntu" or ansible_distribution == "Debian"
+
 - name: Install Certbot.
   package: "name={{ certbot_package }} state=present"
 

vars/Ubuntu-16.04.yml

@@ -1,2 +0,0 @@
----
-certbot_package: letsencrypt