Add stricter json validation and remove positive confirmation that validation passed

Author: scottdj92

schema/schema.json

@@ -1,6 +1,7 @@
 {
   "$schema": "http://json-schema.org/draft-04/schema#",
   "type": "object",
+  "additionalProperties": false,
   "properties": {
     "allChunks": {
       "description": "",

schema/valid.js

@@ -8,7 +8,5 @@ module.exports = function validate(data) {
 
 	if(!valid) {
 		throw new Error("Your ExtractTextPlugin config is not correct. Please double check.");
-	} else {
-		console.log('your stuff works');
 	}
 }