Distinguish modules and endpoints

[dariok]

Everything that is regularly and/or programatically queried (be it from the outside or by the app itself) should be implemented by ways of a RESTful endpoint (stored in edoc/rest).
This endpoint should get its data either directly from the DB or by making use of a module (stored in edoc/modules).

The representations are to be assembled by the REST script while the logic to do so may either be stored in the REST script (if it is static and global) or be provided by a module (usually by project.xqm if it can be project specific). In many cases, a standard representation hard coded into the REST script will be the fallback to a project specific script.