Package names "rdf" and "sparql" are too generic

[jgonggrijp]

The packages already had these names before they were factored out of the READ-IT interface. Now that they are installable through PyPI, however, the names are likely to clash with other packages.

The easiest solution is probably to scope them, for example restyrdf.{rdf,sparql}. Still, any change to the package will require a major version upgrade.

I consider this necessary but non-urgent.