Design and implement PAP backend infrastucture

[Valdas Sevelis]

1. Policy persistence and versioning - research various NoSQL or Document databases
2. An API to access PAP backend for policy management and retrieval

Very interesting read which contains some good ideas
https://wiki.oasis-open.org/xacml/Policy%20Administration%20Point%20Architecture

PAP backend API can be used by PAP UI and PDPs