* I've moved the example secure directory to playbooks/secure_example,
  the directory structure in your secure repo should mirror that in
  secure_example/
* If you run the lms role without a valid git-identity file it will
  fail, there is an empty file checked into the secure_example dir
* Using GIT_SSH env for git checkout, we will also need to use that
  for pip installs that use git if there are private repos in
  requirements.

Also changed top level playbook ymlv var search to follow a path, first
over {{ secure_file_dir }} set in group_vars/all then at
vars/secure_default

* create_users creates an 'edx' group
* create_users task edited to put all admin users in adm and edx groups,
* create_users assigns all users a shell
* lms installs ssh keys for mitx checkout, creates target dir in
  /opt/wwc, and checks out the mitx source

* Created new directory structure outlined in the README
* Created the LMS role which for now just creates teh application config
files
* Created the common role
* Updated the cf playbook to accept arguments