validate policy role for user in a hierarchy

[AlvaroVega]

Study about a custom mode for pep to validate a policy role on a subservice where an user does not have an role assignation but subservice matches with a hierarchy

[AlvaroVega]

Strategy: Iterate validation againts ServicePath suffixes until match it

i.e. ServicePath: /org/city/field
Apply validation for:

                                       servicepath /org/city/field, 
                                       servicepath /org/city, 
                                       servicepath /org

[AlvaroVega]

For orion current FRN is created:
fiware:orion:<service>:/<subservice>:::

[AlvaroVega]

Possible implementation: https://github.com/telefonicaid/fiware-pep-steelskin/blob/master/lib/services/validation.js#L167

Given a subservice composed by several '/', Iterate retrieveRequest from specific to generic