Fix .mil subdomains to prevent false positives

This pull request does three things:

1. Move "United States Air Force Academy" from whitelisting `*.af.mil` to `usafa.af.mil`, its true domain

2. Remove "Air Force Institute of Technology" (also under `navy.mil`) which is now `afit.edu`

3. Move "Naval Postgraduate School" from whitelisting `*.navy.mil` to `nps.navy.mil`, it's true domain (along with `nps.edu`)

/cc @afeld who owns the blame, @dproano who discovered it, and a failing test over in https://github.com/benbalter/gman/pull/72 (where Gman fails to recognize military subdomains due to Swot's overinclusiveness)