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 #369 from claco/issue-597

Merged automatically by jenkins after successful build test
use shared node["osops"]["region"] attribute

remove node["nova"]["compute"]["region"] attr
Merge pull request #370 from invsblduck/issue593_region

Merged automatically by jenkins after successful build test