bump to 0.9.4

package.json

 {
   "name": "fetchblob-dev",
-  "version": "0.9.4-beta.7",
+  "version": "0.9.4",
   "private": true,
   "scripts": {
     "start": "node node_modules/react-native/local-cli/cli.js start",

src/package.json

 {
   "name": "react-native-fetch-blob",
-  "version": "0.9.4-beta.7",
+  "version": "0.9.4",
   "description": "A module provides upload, download, and files access API. Supports file stream read/write for process large files.",
   "main": "index.js",
   "scripts": {