[JIRAALIGN-1567] Export & Import - Features: Export Template Isn't Allowing Users To Import Due To xls File Being Recognized By The Application As xml

Issue Summary

Users export features from the feature grid, then import the file (without making any changes) and receive an error stating that the file can't be imported due to the file type being xml. The odd part here is the user never modifies or changes the file type and the file type extension is still xls. 

Steps to Reproduce

1. Step 1 - Navigate to feature grid
2. Step 2 - Export features
3. Step 3 - Make a small change to the file by renaming, but don't modify the workitems (Make sure you keep the file type xls)
4. Step 4 - Import the renamed file
5. Step 4 - Notice Error (System thinks the xls file is xml)

Expected Results

The export template should be xls, and import successfully. 

Actual Results

Export file is xls, but the system is recognizing the file as xml.

Workaround

Support had to send customers an export template from our internal instance, modify it to ensure no data was there. Then the customers cut and paste the details from their file to ours, and then import their records.