Log headers at trace instead of debug

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -323,7 +323,7 @@ public class S3ProxyHandler {
         for (String headerName : Collections.list(request.getHeaderNames())) {
             for (String headerValue : Collections.list(request.getHeaders(
                     headerName))) {
-                logger.debug("header: {}: {}", headerName,
+                logger.trace("header: {}: {}", headerName,
                         Strings.nullToEmpty(headerValue));
             }
             if (headerName.equalsIgnoreCase(HttpHeaders.DATE)) {