http: Some convenience mods and additions

http: Some convenience mods and additions

* Use cl-http-server routes to route to about, archive, index, etc.

* Don't handle the default page in cl-http-server

* Manage site config by setup-ing/unsetup-ing routes in their respective
  hash tables. We have some default things plus some neat redirects, but
  we still only serve static content at the moment.