[racket] Guard Plugin for Racket Rackunit tests

Although there didn't seem much interest in this when I posted about
it previously, I went ahead and wrote it anyway for myself:  I just
released a ruby gem which will run Rackunit tests as you update your
code.  The source is here: https://github.com/neomantic/guard-rackunit
with installation instructions.  The gem is hosted at rubygems.org:
https://rubygems.org/gems/guard-rackunit.

If anyone needs assistance in using it, please feel free to reach out
to me directly.  Here's hoping that someone finds this useful too.

--
Chad Albers