fixed presenter's handling of incoming data

nodes and edges (as returned by rationalizer) are maps, not arrays
reformatted output of headless tests

highlighting expected vs. actual
created wrapper for simplified initialization

this provides the primary entry point and doubles as the namespace

note, however, that this doesn't completely abstract away the underlying
layers - some awareness of these is still required

the immediate motivation was the need for the fetcher layer to have
access to rationalizer and presenter in some fashion - the details of
this are still being worked out
renamed fetcher references

"provider" was used in the pre-rewrite version, but is no longer
appropriate
created basic SPARQL fetcher

very much incomplete, as evidenced by failing tests
simplified syntax

not sure I like this, but I suppose that's idiomatic CoffeeScript...
simplified fetcher contract

rather than returning nodes and edges, fetchers are now merely expected
to return triples which can be processed by the usual chain
(rationalizer and presenter)

compared to the pre-rewrite version's providers, this removes a whole
lot of interdependencies because fetchers do not have to resolve edges'
source and target into nodes, but just operate on URIs