Add default algorithm of MD5 in readDigestChallenge() if not algorithm token is found in the auth header.

Author: Jeremy Rumpf

src/main/java/me/vzhilin/auth/parser/ChallengeResponseParser.java

@@ -137,6 +137,11 @@ private ChallengeResponse readDigestChallenge(ChallengeResponse challenge) throw
                 readWord(",");
             }
         } while (hasNext());
+
+        if (challenge.getAlgorithm() == null) {
+        	challenge.addAlgorithm(DigestAlgorithm.MD5);
+	}
+
         return challenge;
     }
 }