Rest api stubs

This PR stubs out the REST endpoints for the routes I identified in https://github.com/nodesecurity/nodesecurity-api/issues/1

Currently all the endpoints return HTTP 501 - not implemented. I've stubbed out tests for various access control restrictions (currently all asserting 501 is returned and thus passing) that will need to be finished when the implementation for the REST endpoints is ready.

It exposes the following endpoints:
`GET /aoi/{module_name}/{module_version}` Get a list of AOIs for a particular module@version
`POST /aoi/{module_name}/{module_version}` Create a new AOI for module@version
`GET /reports/{module_name}/{module_version}` Get a list of published vulnerability reports for module@version
`POST /report` Create a new vulnerability report (payload contains module & version details)
`PUT /report/{report_id}` Update a vulnerability report (because I thought that might be useful)