support Iso8601 in date headers

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

@@ -450,10 +450,15 @@ public class S3ProxyHandler {
             } else if (hasDateHeader) {
                 try {
                     dateSkew = request.getDateHeader(HttpHeaders.DATE);
+                    dateSkew /= 1000;
                 } catch (IllegalArgumentException iae) {
-                    throw new S3Exception(S3ErrorCode.ACCESS_DENIED, iae);
+                    try {
+                        dateSkew = parseIso8601(request.getHeader(HttpHeaders.DATE));
+                    } catch (IllegalArgumentException iae2) {
+                        throw new S3Exception(S3ErrorCode.ACCESS_DENIED, iae);
+                    }
                 }
-                dateSkew /= 1000;
+
 
             } else {
                 haveDate = false;