For accessibility purposes the template files notification_error.mustache, notification_info.mustache, notification_success.mustache, notification_warning.mustache in lib/templates should have an aria-label attribute such as aria-label="close".

Currently when using a screen reader such as JAWS or the Google Chrome screen reader extension the close button when focussed it is read as 'multiplication'.

To reproduce the issue:

• Use Google Chrome and install and enable the Screen Reader extension.
• Create a Database Activity in a course, give it a name and hit save and display (note, this issue will be present everywhere the notification templates are used, this is just one example of how to reproduce).
• On the activity page there will be two red error notifications, hit tab until the x (close button) takes focus.
• The Screen Reader extension will read out 'multiplication'.

What I expected to happen:
The Screen Reader extension to read out 'Close', 'Close Button' or something equally descriptive.

What Actually happens:
The Screen Reader extension reads out 'multiplication'.