title: Best way to calculate next date from start plus frequency using joda time
body: <p>I want to work out the next payment date in my code. I have a start date and i have a payment frequency which can be DAY, WEEK, MONTH or YEAR. So if the start date was 10 FEB 2009 and had a payment frequency of MONTH and the current date is 13 NOV 2009 then the next payment date would be 10 DEC 2009 </p>
  
  <p>I have already written some meaty code using JDK data classes to work this out. But we have move other parts of the system to Joda and so i would like to migrate this code to. </p>
  
  <p>So does any Joda guru know how to do it easily?</p>