Make a way to redirect old URLs

[jnga]

With the old domain, make a way to redirect old Go Botany URLs to the new ones. This is important because currently, if one follows an old URL from a bookmark, web page, typing it in, etc., the browser simply times out, making it look like the site is gone. These URLs are easy to map and redirect to the new domain, so we should do that. Perhaps we could set up a simple hosted site for the old domain and upload a list of redirects.

A related issue is #755, that the Go Botany subdomain is not redirecting as it should.