Creating a folder in image uploader should clear cache

[p-decoraid]

Currently when a folder is created in the image uploader it does not show up in the list of files/folders. After the cache is cleared manually, the new folder shows up. The current behavior makes one think folder creation failed when it in reality succeeded.

[p-decoraid]

I see that the added folder does appear when the parent folder has few elements in it. When creating subfolders in a folder with 1500+ files in it the subfolder does not appear without clearing the cache manually.

[owen2345]

Please try again, this should solved by #519