Fixes #4387: Upgrade rudder-server-root 2.9.1 to 2.9.2 fails on rudder-agent on Ubuntu 12.04 LTS
Merge pull request #462 from jooooooon/bug_4387/upgrade_rudder_server_root_2_9_1_to_2_9_2_fails_on_rudder_agent_on_ubuntu_12_04_lts

Fixes #4387: Don't fail on rudder-agent stop, force stop if necessary
Merge branch 'branches/rudder/2.6' into branches/rudder/2.10

Conflicts:
	rudder-agent/SPECS/rudder-agent.spec
Fixes #5500: Clear error log on rudder-upgrade
Merge pull request #478 from VinceMacBuche/bug_5500/upgrade_service_log

Fixes #5500: Clear error log on rudder-upgrade