SAK-25778 - encode and decode uri to create safe ids

git-svn-id: https://source.sakaiproject.org/svn/content/branches/SAK-25778@307090 66ffb92e-73f9-0310-93c1-f5514f145a0a
SAK-25778 - add generic icon for unknowns

git-svn-id: https://source.sakaiproject.org/svn/content/branches/SAK-25778@307091 66ffb92e-73f9-0310-93c1-f5514f145a0a