ACTION-440, Add some test cases to the WIKI page about test cases

Hello,

I have added a set of general test cases to the WIKI for testing e.g. number
of results, test variable binding, test execution time of a query. 

http://www.w3.org/2005/rules/wiki/Category:Test_Case

They are intended as abstract interfaces which can be used in concrete
implementation test cases - see also 

http://www.w3.org/2005/rules/wg/wiki/Arch/Test_Cases

For instance:

RIF Rule Program:
                 q(?X) :- p(?X)
Test Data:
                 p(1^^xsd:Integer)
                 p(2^^xsd:Integer)
                 p(3^^xsd:Integer)

Test Cases:
                 testQuery(q(1^^xsd:Integer))
                 testResult(q(?X),q(3^^xsd:Integer))
                 testQueryTime(q(?X),1000^^xsd:Long)
                 testResults(q(?X),?X,[1,2,3])


The actual implementation of the testQuery "interface" might be rule-based,
e.g.:

testQuery(?Query) :- External(Builtin(Eval(?Query)))

Best, Adrian