Manual employee payment

Today, we are adding the ability for employers to manually pay employees. By default, payment_method is direct_deposit, which tells Check to withdraw that employee's net pay from employer accounts, and directly deposit those funds into the employee's accounts. By defining the payment_method as manual on a payroll item, the employee's net pay will be left in the employer’s bank account. This amount will be for the employer to pay directly to the employee on pay day, whether by check, cash, wire, or another method, while still enabling Check to deduct tax liabilities on those wages from the employer’s bank account.