Add contribution guidance

Add CONTRIBUTING.md that points to the same document in chef-cookbooks
Add mention of the contribution document in the top of the README.md
Merge pull request #57 from claco/contributing

Merged automatically by jenkins after successful build test
Add activebackup capability
Merge pull request #58 from Apsu/activebackup

Merged automatically by jenkins after successful build test
Merge pull request #59 from rackerjoe/grizzly

Merged automatically by jenkins after successful build test