Update ExcelConnection.java

Unfinished WIP code.

To test it use this:

    package org.yats.trader.examples;


        import org.yats.connectivity.excel.ExcelConnection;
    //This class will be used to test the Excel connectivity. It will launch the Excel relative thread in class             ExcelConnection.
    public class ExcelTest {

    public static void main(String[] args){


        ExcelConnection connection=new ExcelConnection("AllGoTrading.xlsx");
        connection.startExcelLink();


    }

}