improve verbose message for package_list_command
Instead of only list arg[0] list while command, eg:
old: Reading package list from /usr/bin/env
new: Reading package list from '/usr/bin/env DEBIAN_FRONTEND=noninteractive LC_ALL=C PATH=/bin:/sbin/:/usr/bin:/usr/sbin /usr/bin/dpkg -l
see discussion in: https://groups.google.com/forum/#!topic/help-cfengine/nH6bR-n2x_c
also adjust message for old log format
Merge pull request #1885 from basvandervlies/improve_verbose_message_for_package_list_command

improve verbose message for package_list_command
Redmine #6441: Fix software_packages.csv being regenerated every time.

Do not allow '\r' to make it into the package string. If the package
manager puts '\r' at the end of the lines, it will cause later
comparisons to fail, so make sure to filter it out.