Add translatable strings to board_type field (#701)

Author: kjonosm

data/fields/board_type.json

@@ -1,5 +1,17 @@
 {
     "key": "board_type",
     "type": "combo",
-    "label": "Type"
+    "label": "Type",
+    "strings": {
+        "options": {
+            "art": "Art",
+            "astronomy": "Astronomy",
+            "geology": "Geology",
+            "history": "History",
+            "nature": "Nature",
+            "plants": "Plants",
+            "welcome_sign": "Welcome Sign",
+            "wildlife": "Wildlife"
+        }
+    }
 }