Make test_cgi pass. I changed the internal file created by make_file()

Make test_cgi pass.  I changed the internal file created by make_file()
to be a text file.  (XXX It should use UTF-8 as the encoding.)
I also removed the unised 'binary' argument from the make_file() signature.

XXX I am under no illusion that this is now working; I're pretty sure
it would be more principled if it always read binary data.  But that's
for someone who actually cares about this module.