Deploy REST API for Salt using rest_cherrypy

Summary:
Salt provides a REST API applications can use to communicate through HTTP.

This deployment is intended to be able to trigger events to the reactor
from external sources like Notifications Center or Jenkins.

It reuses the TLS certificates for Vault as they share the same server.

Ref T1942.

Test Plan: sockstat | grep 8300

Reviewers: dereckson

Maniphest Tasks: T1942

Differential Revision: https://devcentral.nasqueron.org/D3278