fix(setup.py): update to latest OS standards
feat(bastion): a gating middleware

This patchset introduces a middleware (bastion) for gating the routes
of a WSGI app. Bastion operates on exact path matches.

Such a middleware can prove useful for bypassing authentication checks
for a particular route, say, /v1/health, when exposed to a load
balancer.

Closes: #7
Merge pull request #9 from cabrera/api_bastion

feat(bastion): simple, gated routes with back doors