Don't cache real time JSON log

Summary:
Each time a script or software calls /servers-log/all.json,
the server wil serve a real time update.

Test Plan:
Fire a request to the log microservice.

Ask in browser the URL, check it has been updated.

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1317