You can allow for additional file types by adding the extension to the 'ApprovedUploadExtensions' list in ..\Service Catalog\view\conf\ESAPI.properties. Following is from a 14.1 server:
HttpUtilities.ApprovedUploadExtensions=.gif,.tif,.tiff,.jpg,.jpeg,.png,.bmp,.docx,.xlsx,.pptx,.doc,.xls,.ppt,.zip,.jar,.apk,.rar,.pdf,.txt,.xml,.rtf,.properties,.log,.msg,.html,.avi