Switch go Gulp 4 for builds

.gitignore

@@ -1,5 +1,6 @@
 # Do not index node.js modules that are used for building
 node_modules
+package-lock.json
 
 # Do not index releases
 release

README.md

@@ -1,7 +1,7 @@
 # Mibew Operator Status plugin
 Plugin for Mibew, get statement based on the availability of operators.
 
-# Useage
+# Usage
 
 1. Get any operators online status:
  
@@ -20,7 +20,7 @@ Plugin for Mibew, get statement based on the availability of operators.
 
 4. Use callback parameter:
 
-    Just inset `<script>` tag and set `src` to URL above and add `callback` parameter
+    Just insert `<script>` tag and set `src` to URL above and add `callback` parameter
     
     * `<MIBEW-BASE-URL>/opstatus?callback=<CALLBACK_FUNCTION>`
     * `<MIBEW-BASE-URL>/opstatus/<OPERATOR-CODE>?callback=<CALLBACK_FUNCTION>`

gulpfile.js

@@ -21,9 +21,7 @@ gulp.task('prepare-release', function() {
 });
 
 // Builds and packs plugins sources
-gulp.task('default', ['prepare-release'], function() {
-    // The "default" task is just an alias for "prepare-release" task.
-});
+gulp.task('default', gulp.series('prepare-release'));
 
 /**
  * Returns files stream with the plugin sources.

package.json

@@ -1,12 +1,12 @@
 {
   "version": "0.4.0",
   "devDependencies": {
-    "event-stream": "~3.3.1",
-    "gulp": "^3.9.1",
-    "gulp-chmod": "~1.2.0",
+    "event-stream": "3.3.4",
+    "gulp": "^4.0.0",
+    "gulp-chmod": "~3.0.0",
     "gulp-gzip": "~1.1.0",
     "gulp-rename": "~1.2.2",
-    "gulp-tar": "~1.4.0",
+    "gulp-tar": "~3.1.0",
     "gulp-zip": "~3.0.2"
   }
 }