Issue Summary

When adding images from an Android app the attachments are created without a file extension. The file can be opened and viewed from the cardback, but when you download the file it is saved as a file without any extension. 

Steps to Reproduce

1. Go to Trello mobile app for Android
2. Attach a picture to the card (example.jpg)
3. See the attached image in the attachment section (from mobile or web)
4. Download the attached image (from mobile or web) 

Expected Results

The image should be downloaded with the correct file extension (example.jpg)

Actual Results

The image is downloaded without any file extension and can't be opened once you download it (example)

Workaround

No workaround is available at the moment.