Origami allows user to upload any file as sample image

[PalashTanejaPro]

Node version: 8.3.0

npm version: 5.5.1

Operating system: Debian Jesse

Command line used: bash

Steps to reproduce:

1. Go to any origami demo.
2. Try uploading text files and python scripts.

BONUS: If you are the admin of an origami demo, you can do the above steps and upload malicious files and can even run JavaScript on the user's browser.

UPDATE: Have written some code to fix this for the time being. Will make a PR in the morning.

[PalashTanejaPro]

[AvaisP]

@PalashTanejaPro Did you submit a PR for this?