Finish renaming Equipment Objects to Equipment Items

[mnquintana]

Related to #256, #136, sort of #553

We got most of the way to renaming Equipment Objects to Equipment Items, but not quite:

• The route is still equipment_objects/:id
• All the internal identifiers (class names and stuff) are still EquipmentObject(s)

We should:

• Rename the route.
• Add new routes for equipment_objects that redirect to equipment_items (in case any of our users have made bookmarks)
• Decide if we want to rename EquipmentObjects internally. We probably should at this point since it seems like we've been calling them EquipmentItems pretty much exclusively lately.
  • If we do, rename them internally. (this will probably involve a new db migration)

[AlanLiu96]

So do we want to update the EquipmentObjects internally to be EquipmentItems?

[AlanLiu96]

I've added the route for equipment items, but right now the code still all uses equipment objects.