Comply with spec for permissions needed to delete a resource

Basically, until https://github.com/solid/web-access-control-spec/issues/47 gets discussed with a proper decision process, let's undo what was done in https://github.com/solid/node-solid-server/issues/729.

I'm not so fussed about the actual behaviour, I just want to start the process of documenting what we consider the spec (see also https://github.com/solid/solid-spec/issues/174), and on which points we are aware of differences between NSS and the spec.

Wherever such differences exist, if we think that NSS is right, then we should update the spec.
And if we think the spec is right (like in this case), we should (at least create a github issue to) fix NSS.

PS: If anyone is aware of any other points on which NSS is not spec-compliant, then let's create issues for each one of those. We can decide to willingly leave NSS broken, but at least we should have github issues that document how NSS is broken.

Comienza leyendo el issue 47 vinculado de web-access-control-spec, el issue 729 de NSS y el issue 174 de solid-spec para comparar los requisitos de permisos para eliminar un recurso. En el issue no se mencionan archivos ni pruebas; se considera terminado documentar la diferencia entre NSS y spec y registrar la decisión, con un issue posterior de NSS si la implementación debe cambiar.