Ensure the /var/log/apt-cacher-ng directory created

It appears xenial doesn't create this directory by
default, so ensure it's created and set it ot the proper
user/group.

Can reference:
https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1512780

Change-Id: I84e466d7b0230de9e2dd79a9a0b61c2ff1ef40a1

defaults/main.yml

@@ -57,5 +57,9 @@ repo_git_cache_dir: "{{ repo_service_home_folder }}/repo/{{ repo_git_cache_dirna
 repo_pkg_cache_dirname: pkg-cache
 repo_pkg_cache_dir: "{{ repo_service_home_folder }}/repo/{{ repo_pkg_cache_dirname }}"
 
-# Set the Package Cache Service owner
+# Set the Package Cache Service owner and group
 repo_pkg_cache_owner: apt-cacher-ng
+repo_pkg_cache_group: apt-cacher-ng
+
+# Set the log directory
+repo_service_log_dir: /var/log/apt-cacher-ng

tasks/repo_cacher.yml

@@ -68,6 +68,16 @@
   tags:
     - repo_server-install
 
+- name: Create log directory
+  file:
+    path: "{{ repo_service_log_dir }}"
+    state: "directory"
+    owner: "{{ repo_pkg_cache_owner }}"
+    group: "{{ repo_pkg_cache_group }}"
+    mode: "02775"
+  tags:
+    - repo_server-install
+
 - name: Stat the cache path
   stat:
     path: /var/cache/apt-cacher-ng