Added zoom ranges to layers
Added zoom ranges to layers

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