This rolls the ec2 elb management script into a module.
Now if an ELB is added or removed "changed" will return True/False
so you can tell if any action was taken based on the coloring of
the response (yellow/green).

* Use the 'adm' group for permissioning assets needed during LMS
  initialization, because ubuntu doesn't have the edx user until it logs
  out and logs back in.

where it can take a {{ service_variant }} param

* Add ubuntu to edx, restrict git identity access to edx group members

* 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.

* Move debian package list to roles/lms/vars/main.yml
* Move lms_git_repo to roles/lms/vars/main.yml

Return private DNS names that will be resolvale within the VPC. This way
we can define a general SSH config that will work for all hosts.

moved creation of /opt/www and www user into ruby role

* Cleanups in LMS task
* Add missing debian packages: libgeos-dev, nodejs
* Alphabetize list of debian packages in LMS task

* Create a global variable lms_source_repo to make it easy to update
  where to pull mitx from when mitx moves
* Create global variable venv_base to store location of edx virtual
  environment, defaults to /opt/edx
* Create edx virtual environment to store python modules
* Add tags to LMS and CMS tasks to make selective running and testing
  easier
* Install a long, static list of debian packages, which has been
  manually curated from other edx configurations; this probably needs
  more attention and in the future should probably be divided better
  among various roles.
* Install the list of python packages distributed with the mitx
  repository
* Install some really useful software, namely mosh and tmux

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

var empty, so no actual users are created

* Replace hardcoded instances of /opt/wwc with $app_base_dir, which
  defaults to /opt/wwc.
* Add tags to nginx tasks so they can be selected independently.

* 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

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

Looks like there was a copy/paste error, the AMI's that were in there
before were the same as Europe.  These new ones work.

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.

This keeps vars that are specific to roles with the role, not
very well documented except in the playbook example here:
https://github.com/ansible/ansible/blob/devel/examples/playbooks/roletest.yml

This makes playbooks more concise since you do not have to explicitely
include vars for each roles, var_files will still override any of the
default values in <role>/vars/main.yml

Updating default tempalte to point to the multi-instance