HullClassifiers for Utility ships

[zrisher]

I'd like to see a UtilityHullClassifier and a UtilityHullClassifierSmall. Breaking this type of ship into a separate set of categories would give admins a LOT more flexibility on distributing block limits and make it easier to see how ships are being used.

See #19 for priority.

[zrisher]

Actually scratch that, just like Stations I'd like to see a full set of utility ship classes:

• UtilitySmallShipHullClassifier (or similar) - miners, welders, tugs, etc. Small ship. Utility equivalent of a corvette.
• UtilityLargeHullClassifier - larger miners, welders, tugs, + mobile refinery and assembling stations. Large ship. Utility equivalent of a frigate.
• UtilityCarrierHullClassifier - big mobile refinery and assembling stations, hangers, etc. Large ship. Utility equivalent of a cruiser. Probably can have a few turrets.