Add tests to warn when certs/keys expire.
Add tests to warn when certs/keys expire.

Start failing 60 days before the security GPG key or the site
certificate will expire.

codonnell/clojars-web,tobias/clojars-web,clojars/clojars-web,nberger/clojars-web,xeqi/clojars-web,clojars/clojars-web,technomancy/clojars-web,clojars/clojars-web,xeqi/clojars-web,technomancy/clojars-web,codonnell/clojars-web,tobias/clojars-web,ato/clojars-web,dotemacs/clojars-web,dotemacs/clojars-web,ato/clojars-web,nberger/clojars-web,tobias/clojars-web