implemented timeseries resource and update ellaweb service to use it

Timeseries resource functionality:
[GET] /api/v0/timeserie
[PUT] /api/v0/timeserie/:uuid/
  req-body:  {date: unixTimeNumber, value: Number}
  resp-body: {ok:1}
[GET] /api/v0/timeserie/:uuid/hourly
  [[ unixDate1, value1], [unixDate2, valu2], ...]