authomatically compress data

[Rignchen]

every day we get 1440 data and we store them forever, however, the most someone can see on the interface is a 1 hour precision.

Knowing that, keeping 1440 data per day seems overkill, it could be nice if once per day the data from the previous day were compressed to their averaged per hour version
that way we could reduce the storage needed from 1440 data per day to 24 data per day + 1440 data for the current day

[Rignchen]

see #11 for more information about the size of the data