Issue-130 (conformance)

After our discussion during yesterday's Teleconference I have updated  
the Conformance spec [1] to:

- extend the results set to True, False, Unknown, and Error
- more clearly state the conformance requirements on each of the  
profiles
- include a short section on query answering and its relationship to  
entailment checking

Ian

[1] http://www.w3.org/2007/OWL/wiki/Conformance