Bugfix/QRIN-52 swico decimal discounts

QRIN-52: Adds test for defaultPaymentPeriodDays with decimal discounts

QRIN-52: Fixes typos in comment

QRIN-52: Use compareTo instead of equals for BigDecimals

QRIN-52: Use compareTo instead of equals in NumberUtils

QRIN-52: Improves test by using a double