Fix caching of requests for debbie script

[cceckman]

Github appears to add some level of caching to its responses on raw.github.com; for some number of minutes after a commit, I still see the pre-commit contents.

In order to iterate quickly, I should work out how to bypass this.

• Use the Github API, i.e. serving directly from cceckman.com rather than doing an HTTP redirect. This also removes the need for -L.
• Something with HTTP headers to request an uncached version. Cache-Control: max-age= or no-cache?