support for skipping elements in timeseries
add test for bucket
Merge branch 'master' of https://github.com/lunextelecom/timeseries-util
add time selector
Merge branch 'master' of https://github.com/lunextelecom/timeseries-util
Merge branch 'master' of https://github.com/lunextelecom/timeseries-util
Merge branch 'master' of https://github.com/lunextelecom/timeseries-util
add TimeSchedule, Test