Improved log by outputting the Software versions.

- Improved log by outputting the Software versions.
- Reduced code size by using the new `get_cube`.
- Output the processing time for each model url.
- Limited the NaN interpolation to 3 hours (30 potions every 6 min = 3 hours [SABGOM dt]).
- Using 'null' instead of zero for NaN in the series.  (Vega still connects the lines, but it is more appealing this way.)