improve getTriplePattern
nano improvement of a SimpleQuery test case
add basic QueryCache

Implement few functions of a Query Cache described by
a paper of Michael Martin (@MichaelMartin) named:
"Improving the Performance of Semantic Web Applications
with SPARQL Query Caching" (2010)

(Link: http://www.informatik.uni-
leipzig.de/~auer/publication/caching.pdf)