resync called later will now resync with the server
different calculation of round trip time and offset
API returning offset and round trip time
storing the last sync result in localStorage, so we can use it before resyncing next time
Merge pull request #2 from ccoenen/enhancements

Enhancements (localStorage + roundTripTime + offset API) / different calculation

I no longer have a use for this project, so new commits shouldn't be expected from me *but* I will merge cool pulls :) nice work.