Change the version number to be 4.

Author: swftvsn

CHANGELOG.md

@@ -1,5 +1,5 @@
 ## Change Log
-### [6.0.0](https://github.com/georgipeltekov/ngx-file-drop/compare/v3.0.2...v6.0.0) (2018-05-07)
+### [4.0.0](https://github.com/georgipeltekov/ngx-file-drop/compare/v3.0.2...v4.0.0) (2018-05-07)
 * Update to Angular 6.0.0
 
 ### [3.0.2](https://github.com/georgipeltekov/ngx-file-drop/compare/v3.0.1...v3.0.2) (2018-04-29)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ngx-file-drop",
-  "version": "6.0.0",
+  "version": "4.0.0",
   "license": "MIT",
   "scripts": {
     "ng": "ng",