Fixes #5181: Do not use contrib and non-free
Merge pull request #75 from jooooooon/bug_5181/do_not_use_contrib_and_non_free

Fixes #5181: Do not use contrib and non-free
Merge branch 'branches/rudder/2.6' into branches/rudder/2.10

Conflicts:
	11_install_agent/10_install_agent_debian.txt
	12_upgrade/10_upgrade_debian.txt