Refs #4842 - Reduce number of requests of zypper by using a modified generic package_method

Refs #4842 - Reduce number of requests of zypper by using a modified generic package_method

cf http://www.rudder-project.org/redmine/issues/4842

This PR will stop zypper to use useless commands list-update and patch which are extremely verbose in /var/log/zypper.log