improve logging

[bhcopeland]

In GitLab by @terceiro on Jul 21, 2021, 17:50 GMT+1:

• By default, output only the "target" (and "feedback") output
• Display the full LAVA output only in a verbose mode
• Still save the full LAVA output to the log file (?)
• Add option to save only the target log to a log file without all the LAVA output
• display progress when downloading container image

Assignees: bhcopeland

Migrated from GitLab: https://gitlab.com/Linaro/tuxrun/-/issues/23