roles/redis: Add role to deploy Redis

This simple role installs the *redis* package and starts the associated
service.  It leaves the configuration as provided by upstream, at least
for now.

roles/redis/tasks/main.yml

@@ -0,0 +1,15 @@
+- name: ensure redis is installed
+  package:
+    name: redis
+    state: present
+  tags:
+  - install
+
+- name: ensure redis starts at boot
+  service:
+    name: redis
+    enabled: true
+- name: ensure redis is running
+  service:
+    name: redis
+    state: started