Add option to import menstrual cycle data#481

Would be good to be able to sync or import menstrual data from other apps such as fitbit. Or IPeriod (which has export).

Hi @Dremitchell the team is working hard on integrating Migraine Buddy with smart devices. We are starting with sleep tracking and hope to include others eventually.

At least allow the health app to import date to migraine buddy for menstrual dates.