store fetched URI resources only for 1 day in APC cache
document JSON exclusion hack
refactor getResourceFromUri: separate common code to a new private method
refactor: separate try/catch block so it only covers the fetching itself, not unrelated errors
avoid re-fetching URIs, when only the fragment changes
use host name (e.g. dbpedia.org) when cannot find concept scheme for external concept
Merge branch 'master' of https://github.com/NatLibFi/Skosmos into fetch-external-uri