changed Master to Primary in log statement.

Author: Ryan

src/main/com/mongodb/DBTCPConnector.java

@@ -569,7 +569,7 @@ private synchronized boolean setMasterAddress(ServerAddress addr) {
             return false;
 
         if (  _masterPortPool != null )
-            _logger.log(Level.WARNING, "Master switching from " + _masterPortPool.getServerAddress() + " to " + addr);
+            _logger.log(Level.WARNING, "Primary switching from " + _masterPortPool.getServerAddress() + " to " + addr);
         _masterPortPool = newPool;
         return true;
     }