Add log aggregation to kumactl install

[xbauquet]

Summary

The goal for kumactl install to provide a way to aggregate and visualize app logs easily.
I propose to use grafana/Loki to aggregate app logs and visualize then directly into the Grafana installed with the metrics.

This screen shot shows how log visualization with Loki can be used with the traces from Jaeger, if your logs contain the traceId. Some libraries add the traceId into the logs automatically (e.g. Sleuth, for Spring java apps).

[nickolaev]

Fixed in #820