DayOne requires time zone information now

Hi Manuel,

Thanks a lot for your work. I enjoyed jrnl very much. However I got some trouble when I tried to sync the journals with DayOne. For some reason DayOne records the UTC time of each journal plus the time zone of where the journal is written. But jrnl records the local time without time zone information. It causes confusions between two applications. Basically they cannot display correct time for journals written in another application, so the journals are listed completely out of order. 

I wrote this small patch and it worked quite good for me. It adds time zone information to the plist files, and also calculates the correct time and date before initializing entries. I hope other people also find it useful.

Thanks again!

Arapat