Initialize $total_installments

Prevent “notice: undefined …”
Fix "Complete borrower loan" link

The `fillAmount1` javascript function was broken because the form
`#shareTab3Detail` also had “bidform1” as name attribute (copy/paste?)
.
Set default loan amount

Replace the default amount of zero with $30 or the amount still needed
to fully fund the loan, whichever is lesser. See #3.
Set default loan interest rate

If the borrower's on-time repayment rate is less than 90% or they are a
first-time borrower, change the default interest rate in the drop-down
menu from zero to 20%, or to the maximum interest offered by the
borrower, whichever is greater.

If the borrower's on-time repayment rate is 90% or greater, change the
default interest rate in the drop-down menu from zero to 10%, or to the
maximum interest offered by the borrower, whichever is greater.
See #3.