CB-14260: (android) captureImage permission denial on android 8.1 (#95)

* CB-14260: (android) captureImage permission denial on android 8.1
diff --git a/src/android/Capture.java b/src/android/Capture.java
index 40117aa..24578bc 100644
--- a/src/android/Capture.java
+++ b/src/android/Capture.java
@@ -251,16 +251,16 @@
      */
     private void captureImage(Request req) {
         boolean needExternalStoragePermission =
-            !PermissionHelper.hasPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
+            !PermissionHelper.hasPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
 
         boolean needCameraPermission = cameraPermissionInManifest &&
             !PermissionHelper.hasPermission(this, Manifest.permission.CAMERA);
 
         if (needExternalStoragePermission || needCameraPermission) {
             if (needExternalStoragePermission && needCameraPermission) {
-                PermissionHelper.requestPermissions(this, req.requestCode, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.CAMERA});
+                PermissionHelper.requestPermissions(this, req.requestCode, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA});
             } else if (needExternalStoragePermission) {
-                PermissionHelper.requestPermission(this, req.requestCode, Manifest.permission.READ_EXTERNAL_STORAGE);
+                PermissionHelper.requestPermission(this, req.requestCode, Manifest.permission.WRITE_EXTERNAL_STORAGE);
             } else {
                 PermissionHelper.requestPermission(this, req.requestCode, Manifest.permission.CAMERA);
             }