Remove obsolete skeletron queries.

queries/skeletron-z(15, 16).pgsql
	-Remove the two skeletron queries because we don't use them any
	longer.
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.
Merge pull request #61 from sevko/master

Remove obsolete skeletron queries.