Time tracking (time warrior integration)

[ronstone2000]

First - great project and thanks for putting it out there.

This may be a refinement of https://github.com/DCsunset/taskwarrior-webui/issues/19. I'd be very interested in start/stop that can take advantage of time warrior and the associated on-modify hook to cumulatively time activities. Unfortunately I don't have the skills to implement it myself.