Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Demo/sockets/ftp.py b/Demo/sockets/ftp.py
index 8260c52..9e1d5a1 100755
--- a/Demo/sockets/ftp.py
+++ b/Demo/sockets/ftp.py
@@ -91,7 +91,7 @@
 	hostname = gethostname()
 	hostaddr = gethostbyname(hostname)
 	hbytes = string.splitfields(hostaddr, '.')
-	pbytes = [`port/256`, `port%256`]
+	pbytes = [repr(port/256), repr(port%256)]
 	bytes = hbytes + pbytes
 	cmd = 'PORT ' + string.joinfields(bytes, ',')
 	s.send(cmd + '\r\n')