fasting plugin edit start/stop time 

Hi - thanks for all of the great work on keeping up Nomie, just getting into it.

I've added the fasting plugin and thinmk it would be great if possible to edit start and finish times for fasts - e.g. if you forgot to begin it immediately, change your mind about eating again, etc. With that think functionality would be comparable to most standalone fasting apps. 

Best - mc