Initial definition of the worker boxes in cloudformation.

Extract the app port numbers into the vars file.

The number of workers need a multiplier, which I missed in code review

Make the condition on migrate_db a bit safer for using in var_prompt

Use ansible facts instead of facter.

The ansible_processor field provides a list of all hyperthreaded cores. Using
Jinja we can just get the number of cores on the machine by running length on
this list.

Use Relative pathes for ora and xqueue auth.json and env.json

Feanil/vagrant updates

Swap lms and lms-xml nginx ports and remove edxapp_sandbox.yml from vars_files because it no longer exists.

Putting migratedb in group_vars/all overrides any vars
in playbook files and so migrations never get run.

In regular runs it seems to have no side effect but fails for vagrant runs.

Feanil/ansible workers rebase

This also makes it easier to conditionalize it since it
doesn't need to be run on workers.

Jarv/ansible version fix deploy

Fixes bug where WORKERS was sometimes being set to "NAN"

For the case where  "ansible_processor_cores": "NA"  and
facter_processorcount wasn't the WORKERS was set to the string "NA" *
the multiplier (like batman).
This will try to convert both to numbers and if the conversion fails it
will fall through and just set the WORKERS to the multiplier.

Jarv/single instance fixes

removing README.md content in favor of the wiki