Change Tracking of RDF example document.

[monkeyiq <monkeyiq@gmail.com>]

Hi,
  This uses nquads to serialize the RDF "data" file so that graph
contexts are preserved. Note that it is a hand created example, so there
might be a glitch or two in there.

  At first it was tempting to try to share a graph context for all
triples created in ct1. However, when it comes to trying to update the
phone number for <uri:joyce>, one must somehow retract just the triple
for their old phone number. Having an explicit context per triple makes
this retraction much simpler.

change-tracking-rdf.odt