Adds empty into schema for node (webpack#3034)

Akkuma · sokra · commit 259cf68b90cb · 2016-09-21T00:24:38.000+02:00
Support for empty was broken through the schema, so I've added it back.
diff --git a/schemas/webpackOptionsSchema.json b/schemas/webpackOptionsSchema.json
@@ -665,7 +665,8 @@
         "enum": [
           false,
           true,
-          "mock"
+          "mock",
+          "empty"
         ]
       },
       "properties": {
