flag to disable progress output

[kjetilho]

when running from cron, the progress output is a distraction from the log files. this patch adds an option to turn it off, and also an option to increase verbosity for debugging.

[kjetilho]

example output with --no-progress:

Downloading 1910 index files using 10 threads...
Downloading 33 translation files using 10 threads...
Downloading 0 dep11 files using 0 threads...
44.4 MiB will be downloaded into archive.
Downloading 1 archive files using 1 threads...
0 bytes in 0 files and 0 directories can be freed.
Run /srv/aptmirror/var/clean.sh for this purpose.

Running the Post Mirror script ...
(/srv/aptmirror/var/postmirror.sh)

Removing 0 unnecessary files [0 bytes]...
done.

Removing 0 unnecessary directories...
done.


Post Mirror script has completed. See above output for any possible errors.