Let ammo be specified in the JSON raws
Moved ammo defs to json raws
Move gasoline to json raws
Fix types and ammo_types
Fix up item descriptions
Set phase for gasoline to liquid.

Requires pull request #939 or #941 to function.
Merge pull request #928 from fergus-dall/ammo-json

Adds ammo handling to item factorys, and moves ammo definitions to JSON raws