moved var and task to ruby role per @jarv

playbooks/group_vars/all

 ---
 app_base_dir: /opt/wwc
-ruby_base: /opt/www
 
 #where are the secure files on the deploying machine?
 secure_file_dir: ../../edx-secret/ansible/vars/

playbooks/roles/common/tasks/main.yml

@@ -3,9 +3,6 @@
 - name: Create application root
   sudo: True
   file: path=$app_base_dir state=directory owner=root group=root
-- name: Create ruby base
-  sudo: True
-  file: path=$ruby_base state=directory owner=www group=www
 - name: Create log directory
   sudo: True
   file: path=/mnt/logs state=directory

playbooks/roles/ruby/tasks/main.yml

 #
 #cribbed from https://github.com/mmoya/ansible-playbooks/blob/master/rbenv/main.yml
+- name: Create ruby base
+  sudo: True
+  file: path=$ruby_base state=directory owner=www group=www
 - name: rbenv | install build depends
   sudo: true
   apt: pkg=$item state=present install_recommends=no

playbooks/roles/ruby/vars/main.yml

 ---
+ruby_base: /opt/www
 rbenv_root: "{{ ruby_base }}/.rbenv"
 ruby_version: "1.9.3-p374"
 gem_home: "{{ ruby_base }}/.gem"