log level propagation from mirror.py to Command

[vladak]

Describe the bug
As I was debugging a case where the incoming check hung mirror.py for some reason for a project with number of Mercurial repositories (might be a subject of another bug to be filed) I noticed that even though I specified log level as DEBUG, the functions inside the Command class did not log expected output - as if the log level was still set default.

To Reproduce
run opengrok-mirror with -l DEBUG on a project

Expected behavior
logging in the Command class used by mirror.py should follow the log level, no matter if batch logging (-b) is set.

[vladak]

Similarly for functions in utils/mirror.py - things like reporting ignored repositories.