Fixes #3880: only accept/refuse node by node to not loose errors
Merge pull request #305 from fanf/bug_3880/missing_errors_when_accepting_nodes

Fixes #3880: only accept/refuse node by node to not loose errors
Merge branch 'branches/rudder/2.4' into branches/rudder/2.6

Conflicts:
	rudder-core/src/main/scala/com/normation/rudder/services/servers/NewNodeManager.scala
	rudder-web/src/main/scala/com/normation/rudder/web/snippet/node/AcceptNode.scala
Merge branch 'branches/rudder/2.6' into branches/rudder/2.7
Ref #3880 : Adap Node API to use new Accept/refuse node functions