Fix visiblity of LiskDAO::getConfiguration()
Summary: Ref T6822.
Test Plan: grep
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: hach-que, Korvin, epriestley
Maniphest Tasks: T6822
Differential Revision: https://secure.phabricator.com/D11370