banana-sesame should do some basic semantic validation when creating literals

[betehess]

The problem was exposed in banana-rdf/banana-ldpatch#1.

In SesameOps, LiteralImpl is being used. But that class doesn't do any validation:

scala> import org.openrdf.model.impl._
import org.openrdf.model.impl._

scala> new LiteralImpl("foo", new URIImpl("http://www.w3.org/2001/XMLSchema#boolean"))
res3: org.openrdf.model.impl.LiteralImpl = "foo"^^<http://www.w3.org/2001/XMLSchema#boolean>

There is an easy way to fix that: makeLiteral should look at the datatype being used, and for those that make sense, we should do some simple validation, and even use the most specialized classes for those types.

For example, in the case above, we should be using BooleanLiteral instead.