change over the zoom stuff to scale within the postproccessor
fix up automatic cast between double and int. remove comments about 'level'
realized that the mapnik::map object has most everything that we might want for post processing so switched over to sending that
update incorrect comment about scale/zoom
add test for zoom range check but need to on the fly convert zoom to scale for choosing whether to apply the izer or not
fix up happy path zoom selection for 900913 projections. should be easier to do other projections if need be
forgot the test file
make it a little easier to avoid problems with precision
Merge pull request #30 from MapQuest/kk_zoomtoscale

let the postprocessors use the mapnik::map object intellegently