Initial code review changes.
Add guards in execute to make registration/unregistration idempotent.
Added comments to register and unregister recipes.
Update README.md
Added RHEL 7 to requirements in README.
Adding badges to README.
Added several dev files.
Start dev on serverspec tests.
Create Strainerfile
Access node attributes in a consistent manner.
Add serverspec tests.
Merge pull request #1 from rightscale-cookbooks/st_14_13_acu173881_redhat_subscription_manager

Initial code review changes.