Remove skeletron references from tilestache.cfg.
Remove skeletron references from tilestache.cfg.

tilestache.cfg
	-Remove the now superfluous top level keys `"skeletron"` and
	`"skeletron-2x"` and their corresponding values, as the
	skeletron queries were removed in 55e8747.

adncentral/vector-datasource,adncentral/vector-datasource,mapzen/vector-datasource,zoondka/vector-datasource,adncentral/vector-datasource,gronke/vector-datasource,kyroskoh/vector-datasource,mapzen/vector-datasource,zoondka/vector-datasource,mapzen/vector-datasource,gronke/vector-datasource,adncentral/vector-datasource,kyroskoh/vector-datasource