WIP: add new promises to stack/monitor

Branch on slapos.toolbox with new promises here and the MR https://lab.nexedi.com/nexedi/slapos.toolbox/merge_requests/99

The goal is to be able to use the pandas libraries in the monitor_partition_space.py promise and pandas/scipy/statsmodels in the check_free_disk_space.py promise to use the new ARIMA option to predict the remaining disk space. There are now in stack/monitor the two new updated promises.

Concerning the check_free_disk_space promise, the display-partition-check-free-disk-space option is enabled by default but not the display-prediction-check-free-disk-space option. To use ARIMA, you have to modify the SR as you can see (theia here):

[monitor-instance-parameter]
# change the value of "display-prediction" to 1 to use ARIMA in the check_free_disk_space promise
display-prediction-check-free-disk-space = {{ parameter_dict.get('display-prediction', 0) }}
# by default the prediction will be for the next 10 days, this parameter can be changed below
days-check-free-disk-space =

Theia extends the [monitor-instance-parameter] section of monitor and by modifying the display-prediction parameter (slapos request ... --parameters display-prediction=1), theia will use the prediction in the promise.

I also add the display-anomaly parameter which allows to use the monitor_partition_space promise only if the user wants it (slapos request ... --parameters display-anomaly=1).

In these changes, the new modules (pandas, statsmodels and scipy) are currently compiled by default.

The Test Suite (in progress)