add missing values to crane type crane field (#662)

Author: k-yle

data/fields/crane/type.json

@@ -6,7 +6,9 @@
         "options": {
             "portal_crane": "Portal Crane",
             "floor-mounted_crane": "Floor-mounted Crane",
-            "travel_lift": "Travel Lift"
+            "travel_lift": "Travel Lift",
+            "gantry_crane": "Gantry Crane",
+            "tower_crane": "Tower Crane"
         }
     },
     "autoSuggestions": false,