Fixing bugs, adding options, and adding more to readme.

Fixed issues with Billing Admins Group ACL not being properly backed up.
Fixed restoration of User ACLs but still relies on OC-10799 to be merged.
Added chef_server_root, similarly to what Knife-OPC does so that a user can still use their standard knife.rb file.
Added option to skip User ACLs for users running unpatched versions of OPC and EC.
Added more to readme so that users can more easily just install, quickly read, and start using it.
Restructured readme to fit more inline with GitHub's Flavored Markdown practices. I hope that is okay :)