Release version 4.

README.md

@@ -30,7 +30,7 @@ Hit back and try another one!
 
 # Changelog
 
- * Version 4 (**pending release**)
+ * Version 4 (Aug 20, 2017)
    * Rewritten as WebExtension with major contributions
      by [Tobias Girstmair](https://gir.st/)
      * Does not include netError page

manifest.json

@@ -8,7 +8,7 @@
   "applications": {
     "gecko": {
       "id": "{0c8fbd76-bdeb-4c52-9b24-d587ce7b9dc3}",
-      "strict_min_version": "56.0b3"
+      "strict_min_version": "57.0"
     }
   },