product recommendation - Hebrew Calender API/Library in PHP or Javascript to add days, month or years to Julian date

I have a web project where I need a function either server-side using php or client-side using javascript where I can pass in a Georgian date and have month(s) or years added to it according to the Hebrew calendar, and return a Julian date.

for example the date 12/8/2014 which is 15 Kislev when adding a month it should return 1/7/2014 which is the Hebrew date of 15 Tevet instead of 1/8/2014 which is returned by regular date add functions which is actually 16 Tevet.

I've searched around and couldn't find anything, Hebcal doesn't seem to have any of these params.