dclib x.fetch() seem to only ask for .ttl

[skwlilac]

DCLIB's x.fetch function only seems to ask for.ttl responses. Some RDF sites are capable of supplying RDF/XML but don't offer turtle, eg. companies house linked-data:

`http://business.data.gov.uk/id/company/01649776`

The following DCLIB warning arises when a .fetch() operation is performed on that URI

12:40:39.253 Warning: exception fetching http://business.data.gov.uk/id/company/01649776, org.apache.jena.atlas.web.HttpException: 406 - Unsupported content type: ttl

It would be useful if DCLIB made requests that also accept RDF/XML responses (may be it does already, in which case it may be an issue with the way this particular site responds).