Fixes #5579: Send reports from the agent to provide a heartbeat
Fixes #5826: Add _ok in rudder_common_classes
Merge pull request #568 from peckpeck/bug_5826/add_ok_in_rudder_common_classes

Fixes #5826: Add _ok in rudder_common_classes
Merge pull request #565 from jooooooon/dev_5579/send_reports_from_the_agent_to_provide_a_heartbeat

Fixes #5579: Send reports from the agent to provide a heartbeat
Fixes #5827: Add a technique to send send metrics
Merge pull request #569 from peckpeck/dev_5827/add_a_technique_to_send_send_metrics

Fixes #5827: Add a technique to send send metrics
Fixes #5643: add support for environment variable through ${node.env[XXX]} notation
Merge pull request #564 from ncharles/ust_5449/dev/5643_env_variables_3_0

Fixes #5643: add support for environment variable through ${node.env[XXX...
Fixes #5790: Deprecate ZypperManagement Technique
Merge pull request #570 from ncharles/bug_5790/dev/deprecate_zypper

Fixes #5790: Deprecate ZypperManagement Technique
Fixes #5689: Rewrite system techniques to use rudder_common_report