Issue 2215: Error 500 on GE Summary page

Resolves issue: http://code.google.com/p/otwarchive/issues/detail?id=2215
When there is no information to display in the table, we leave a notice saying that no tags were used in the challenge. 
No need to do immediately, but I need to note it or I'll forget I reviewed this: it would be good to remove the deprecated dashes before the %> sign - it used to be needed for resulting well laid-out HTML, but now it's not needed any more.

Good to go otherwise.