Integration test for ConfigReport

Summary:
A simple integration test for /config output,
to check output of code introduced at f3fcf394ac9c.

Services mockery is moved to base TestCase class,
as now needed at two places, config:show command
and /config route.

Test Plan: Run tests

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D789