Resource icon alt text in the course page does not have the file type that is conveyed by the icon

Issue
Resource activity icons on the course page have an alt text set to resource, however the icon changes based on the type of file that has been uploaded to the resource. Because activity icons are used to convey meaning in the moodle course page the alt text for a resource should include the type of file that has been uploaded. This text shoudl convey the same meaning that a sited user gains by viewing the icon.

Standard Level
WCAG 2 1.1.1 (A) http://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv-all.html

Impact
Serious

Example Link
http://demo.moodle.net/

Test Steps

1. Navigate to a course page
2. Create a file resource
3. Upload a pdf
4. Inspect the code around an activity icon and see that alt text does not reflect that a PDF has been uploaded.