Fixes #5577: Add Backend and UI for Heartbeat configuration feature
Merge pull request #665 from VinceMacBuche/ust_5576/implem_5577/Heartbeat_ui_backend

Fixes #5577: Add Backend and UI for Heartbeat configuration feature
Merge branch 'branches/rudder/3.0'

Conflicts:
	rudder-core/src/main/scala/com/normation/rudder/services/policies/DeploymentService.scala