Modification to Slideshare

- mui library now returns the full HTML link provided by SlideShare as content if it was verified as a SlideShare link (no 404 error), link includes author's name and links
- Slideshare-v now uses full HTML link provided instead of inserting only the id in a pre-set embed frame
- materials table modified for larger field to accommodate longer HTML link
- skilljoy database with old slideshare content format removed and with the new modified materials table