make nginx.conf overriding optional

If the nginx play is called with the nginx_conf varialble, then expect
to find in {{secure_dir}}/files/nginx.conf and copy it over.  If not set
then the default one already there will be sufficient.

playbooks/edx-west/carnegie-prod-app.yml

@@ -15,7 +15,7 @@
     - "{{ secure_dir }}/vars/edxapp_prod_users.yml"
   roles:
     - common
-    - nginx
+    - {'role': 'nginx', 'nginx_conf': true} 
     - {'role': 'edxapp', 'openid_workaround': true, 'template_subdir': 'carnegie'}
     # run this role last
     # - in_production

playbooks/edx-west/stage-ansible.cfg

@@ -8,7 +8,7 @@ hash_behaviour=merge
 # These are environment-specific defaults
 forks=10
 #forks=1
-log_path=stage-edx-ansible.log
+log_path=~/stage-edx-ansible.log
 transport=ssh
 hostfile=./ec2.py
 extra_vars='key=deployment name=edx-stage group=edx-stage region=us-west-1'
@@ -16,6 +16,5 @@ user=ubuntu
 
 [ssh_connection]
 # example from https://github.com/ansible/ansible/blob/devel/examples/ansible.cfg
-#ssh_args=-o ControlMaster=auto -o ControlPersist=60s -o ControlPath=/tmp/ansible-ssh-%h-%p-%r
 ssh_args=-F stage-ssh-config -o ControlMaster=auto -o ControlPersist=60s -o ControlPath=/tmp/ansible-ssh-%h-%p-%r
 scp_if_ssh=True

playbooks/roles/nginx/tasks/main.yml

@@ -10,6 +10,7 @@
 
 - name: nginx | Server configuration file
   copy: src={{secure_dir}}/files/nginx.conf dest=/etc/nginx/nginx.conf owner=root group=root mode=0644
+  when: nginx_conf is defined
   notify: nginx | restart nginx
   tags:
   - nginx