Logout doesn't clear file names stored in cache

[FilomenoSanchez]

Describe the bug
When a user logouts the file names stored in the cache are not cleaned

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Login' and login into user account
2. Go to 'Plot' and generate a plot
3. Logout of user account
4. Go back to 'Plot'
5. Attempt to upload a file that was uploaded while logged in but should no longer be kept in the memory
6. "File already uploaded" alert

Expected behaviour
The file should be uploaded without problems