#31 make localPart of REST resources a proper NCName

[Egon Willighagen]

Allowing them to be properly namespaced in RDF serialization formats.

So, start the localPart with a 'a-z' or 'A-Z', and have as default URI for a dataset:

http://apps.ideaconsult.net:8080/ambit2/dataset/d291800

rather than

http://apps.ideaconsult.net:8080/ambit2/dataset/291800

This would allow this set up in N3:

@prefix abds; <http://apps.ideaconsult.net:8080/ambit2/dataset/>

abds:d291800

And that in return can durther reduce triple download sizes.