upated PachubeClientString to fix interval bug

Author: tigoe

examples/PachubeClientString/PachubeClientString.ino

@@ -45,7 +45,7 @@ IPAddress ip(10,0,0,20);
 // initialize the library instance:
 EthernetClient client;
 
-long lastConnectionTime = 0;        // last time you connected to the server, in milliseconds
+unsigned long lastConnectionTime = 0;        // last time you connected to the server, in milliseconds
 boolean lastConnected = false;      // state of the connection last time through the main loop
 const unsigned long postingInterval = 10000;  //delay between updates to Pachube.com