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

Allow xqueue to access the existing RDS.

First pass at a vagrantfile that uses ansible to set up all edx apps

Get end to end grader testing working.

Need an extra package if we're using debian for rabbit clustering.