Now QueryRewriter is used in dataview objects they can decide
whether overviews are applicable, have the oportunity to
adapt queries for overviews, etc.
This is done by having overviews-related behaviour in models/dataview/overviews
and falling back to the regular models/dataview.
QueryRewriter should be passed the query that would be used otherwise.
If QR cannot handle it, it will be returned unmodified.
So QR must be used when a query has been prepared and the result
of QR should be used to replace it.
This requires the QueryRewriter to handle a filters parametes in
its data (with Camshaft filter definitions) and a final
options parameters with a bounding_box parameter.
Javier Goizueta