mbtiles tiletype/info mismatches

[rclark]

Useless unit test needs to be remedied. I need an mbtiles file that contains a tile that tiletype doesn't recognize.

Also, should mark invalid mbtiles files where the metadata table says the format is one thing, but it does not match the tiles themselves. Many of these fixtures fall into this trap, so this is going to mean editing them manually and testing for a failure