LILY-1003 namespace prefixes in REST itf optional

In the REST interface, make it possible to retrieve JSON representations of records and schema types without namespaces prefixes, rather using full names in "{namespace}name" style instead. This is done by adding a request parameter ?nsprefixes=false. The default behavior stays unchanged.

Related, allow using such full names as well in URL's (they were previously already supported in the JSON formats submitted towards the server).