Upload csv file from windows machine does not work

[Rita-C]

Steps to produce:
On a windows computer when using Firefox/MS Edge browsers:

1. Login to lists.ala.org.au, click "upload a list" button
2. Use option 1 - select a CSV file to upload, select a file then check data

Expected result:
File accepted

Actually result:
"Invalid file type" error displayed.

Users able to copy and paste data to proceed.
Issue requires code fix adding new ACCEPTED_CONTENT_TYPES - "application/vnd.ms-excel"
The problem is due to how the mime-type of a file is determined by the browser. Window passes 'application/vnd.ms-excel' as the file type for csv files. Chrome manages the file type however Firefox/MS Edge need it explicitly defined.