Issue Summary

When attempting to export a Trello board, users are prompted to install a 'blob' app to view the file. 

Steps to Reproduce

1. Open your desktop app.
2. Access a board.
3. Try to export a board following the steps outlined here. 
4. The board is not exported and you'll see the message below.
   

Expected Results

Export the board the same way it was exported before.

Actual Results

The board is not being exported at all.

Workaround

In the meantime, please try exporting your boards directly from your browser