fix minus signs in tilestache-clean manpage
fix minus signs in tilestache-clean manpage

moskvax/TileStache,SEL-Columbia/TileStache,Billups/TileStache,Blechhirn/TileStache,TileStache/TileStache,Blechhirn/TileStache,mojodna/TileStache,TileStache/TileStache,moskvax/TileStache,Blechhirn/TileStache,moskvax/TileStache,SEL-Columbia/TileStache,SEL-Columbia/TileStache,TileStache/TileStache,jbants/TileStache,MetGIS/TileStache,Billups/TileStache,mojodna/TileStache,Kosta-Github/TileStache,jbants/TileStache,MetGIS/TileStache,Kosta-Github/TileStache,mapzen/TileStache,Kosta-Github/TileStache,Billups/TileStache,mapzen/TileStache,jbants/TileStache,mapzen/TileStache,MetGIS/TileStache