Create picnic_table.json

Can be used for several tourism related features. Also see #736

Author: kjonosm

data/fields/picnic_table.json

@@ -0,0 +1,9 @@
+{
+    "key": "picnic_table",
+    "type": "check",
+    "label": "Picnic Table",
+    "terms": [
+        "outdoor table",
+        "bench"
+    ]
+}