Mortgage refinancing jumped sharply higher for the second straight week, as interest rates fell further, but that boom may be about to bust. Interest rates are now moving much higher. Last week, applications to refinance a home loan rose 20% compared with the previous week, according to the Mortgage Bankers Association's seasonally adjusted index. Applications were 183% higher than the same week one year ago. The average contract interest rate for 30-year fixed-rate mortgages with conforming