Fix java.lang.StackOverflowError in getSql

getSql was calling itself by checking (!sql).  I assume the original
intention was to create a local sql instance property and set it on the
first call, but return the same instance after that.
adding sql closure test to test.changelog
Merge pull request #20 from aaronzirbes/hotfix/get-sql-stackoverflow

Fix java.lang.StackOverflowError in getSql