Refactor how we manage secure data, git-identity changes

* 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.
resolving merge conflicts
readme update
fix bug in pathing add var/
Merge pull request #28 from edx/jarv/secure-refactor

Refactor how we manage secure data, git-identity changes