Delete a DataNode under a given anchor by 'full' xpath

Delete single entry in list (using key-value identifier as per xpath) should be possible too 

Will also delete all children 

Available on CPS-REST API

Extended validation i.e compulsory children (assuming this could be defined in Yang) is not covered in this user story as we do not have 'extended' validation at all yet

Edge-cases to consider/discuss

• last element of list is removed
• remove top level DataNode, this well leave an 'empty' anchor is that OK?