Added auto detection of external ip address

TODO

@@ -3,9 +3,6 @@ TODO for dnsupdate
 - Check if address needs update before sending data
 - Add a config-file for hostname, domain and password
   All options should be configurable, ttl and force as well.
-- Auto-detect the machine's external ip address'
-  Should work on OS X, Linux and Windows. 
-  Should work with multiple interfaces.
 - Have options to delete a server as well as add/update
 - Integrate the relevant dnspython modules
 - Add a GUI
@@ -22,3 +19,7 @@ Done:
   -n hostname
   -p password
   -t ttl
+- Auto-detect the machine's external ip address'
+  Should work on OS X, Linux and Windows. 
+  Should work with multiple interfaces.
+  http://www.showmyip.com/simple eller skriva en egen.