Changes

Bug 521786 - OSLC Query: Exception when requesting the type of a URI
operand

All "syster" classes that extend ValueInvocationHandler (such as
StringValueInvocationHandler & BooleanValueInvocationHandler), actually
return the response from the super class.
UriRef...Handler seems to simply call super.invoke(...) and do nothing
with the result.

Signed-off-by: Jad El-khoury <jad@kth.se>