Updating to work with CHICKEN 5.

Updated to work with CHICKEN 5. Thanks to Andy Bennett
<andyjpb@ashurst.eu.org> for doing most of the work!

Moved hmac.release-info* uri targz to point at code.thintz.com instead
of github.

tests/run.scm

@@ -2,8 +2,16 @@
 ; email: t@thintz.com
 ; license: bsd
 
-(use test)
-(use sha1 string-utils hmac)
+(cond-expand
+
+  (chicken-4
+    (use test)
+    (use sha1 string-utils hmac))
+
+  (chicken-5
+    (import test)
+    (import sha1 string-hexadecimal hmac)))
+
 
 (test-group "RFC2202 test vectors"
   (define (testv key msg expected)