wip:MIFOSX-244 Adding Calendar RecurringRule

Hi Keith,

This commit includes validation for recurring rule. I have added ical4j jar in build.gradle which requires eclipse clean build.

I am working on
          1. making converting recurring rule to human readable.
          2. Adding generic methods around calendar to get next recurring date, list of recurring dates and validate a selected date against the available calendar dates.

Regards
Ashok