Fix for Bug 7083 - [SIGNED-OFF] Show creator name on list of public lists

Fix for Bug 7083 - [SIGNED-OFF] Show creator name on list of public lists

Show the name of the patron who created each list on the list
of public lists. Also:

- correcting unescaped ampersand in the template
- making conditional a check on a variable that doesn't always
  exist, causing noisy errors in the log

Signed-off-by: Magnus Enger <magnus@enger.priv.no>
After applying the patch a column for "Created by" is added to the display of
public lists, and the errors in the log are silenced. On the "Your lists"
tab, the link on the list name now has an escaped ampersand.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>