add handler for fresh start without database file

import edu.bu.ec504.project.Molecule;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

     * Load database from file system

     */

    public void load(String filename) throws IOException {

        File dbFile = new File(filename);

        if (!dbFile.exists()) {

            this.save(filename);

        }

        FileInputStream fileInStream = new FileInputStream(filename);

        ObjectInputStream objInStream = new ObjectInputStream(fileInStream);

        try {