LPS-39698 Loan Calculator functions again

Previous commit included bootstrap styling and using taglibs, but made it
so that the portlet did not function. Problems that are now fixed:
* Name attributes of the input fields were inconsistent with the ParamUtil
   get requests, so the values were not read in from the input fields
* Loan amount:
   * Problems caused by trying to format the number nicely as a string,
      but then trying to use it in computations
   * If you want to format loanAmount with an instance of NumberFormat
      (such as integerFormat), you have to get it as a string and then
      convert it to an integer. This is the solution used in this version
      * Alternatively, if you don't format it (in the value field of the
         input), you would be able to read it in as an int with ParamUtil.
      * However, this would not look as nice in the portlet UI
* Form didn't do anything when Calculate button was clicked
   * portlet:actionURL was changed to portlet:renderURL