* 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.

By default it installs 1.9.3-p374 in /opt/www/.rbenv and gems go
in /opt/www/.gem, which replicates the vagrant box

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

By default ansible will load libs in library/ which means
you do not need to specify a module path if you are invoking
ansible from the playbooks/ dir.

Added some comments to the rolling example

Requires the latest ansible to use (you may need to remove and add it again if
you are in a virtualenv)

See `edxapp_rolling_example.yml`

A new module is necessary for ELB information since that is not
available in EC2 metadata (which is what ec2_facts fetches).

ec2_facts grabs the instance ids and other meta information
ec2_elb_facts fetches ELB information
elb_reg.py takes an elb and instance id and will either register or
deregister. (called as pre and post).

`Serial` should be set to the number of instances that you want to
operate on simultaneously, currently set to 1.