Fix FC019: Access node attributes in a consistent manner

Use either symbols or strings, but not both
Install v1.5.2 of Exhibitor

Driver of moving to this version is fixes to the rolling config change

See
https://raw.githubusercontent.com/Netflix/exhibitor/master/CHANGES.txt
for details
Move Test Kitchen data to standard location

* Remove all but a few data bags
* Clean up test environments
Clean up & update Test Kitchen config, add commented-out EC2 driver

If one wishes to test w/ EC2 instead of Vagrant:

1. Uncomment the EC2 driver settings (name, tags)
2. Comment out `name: vagrant` in driver section
3. Comment out the provisioner name (`chef_zero`)
Remove Thorfile & Vagrantfile in favor of Test Kitchen
Update Gemfile to use various handy tools, add Rakefile

Rakefile has all manner of excellent testing tasks ready to go
Fix Berksfile to use Berkshelf API Server (compatible w/ Berkshelf 3)
Include apt::default to try & encourage `apt-get update` to run
Ignore particular Rubocop Cop for metadata for readability
Add ChefSpec tests
Add ServerSpec integration tests
Update CHANGELOG to follow Stove's syntax