Use new get_mysql_endpoint method in osops-utils

Start converting various cookbooks to use the new #get_mysql_endpoint method
which now allows people to point to a non-chef managed mysql server for all
things.

See rcbops/chef-cookbooks#597
Merge pull request #186 from claco/issue-597

Merged automatically by jenkins after successful build test
use global 'region' attr
Merge pull request #187 from invsblduck/issue593_region

Merged automatically by jenkins after successful build test
Update README.md with rbd attributes