Fixes #3967 : Improve change request merge check:

Ldap datas are transformed in XML, then checked, before being
unserialised to their types
Merge pull request #326 from VinceMacBuche/bug_3967/serialize_deserialize_ldap_into_xmll

Fixes #3967 : Improve change request merge check:
Merge branch 'branches/rudder/2.6' into branches/rudder/2.7

Conflicts:
	rudder-core/src/main/scala/com/normation/rudder/services/workflows/CommitAndDeployChangeRequestService.scala