Migrate data/servers.json to Salt deployment

Summary:
This change allows a better separation between code logic and configuration.

This is a follow-up for rOPS ae7ed5e6e225.

Ref T1412.

Test Plan: no op

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1412

Differential Revision: http://devcentral.nasqueron.org/D1685