Fix the math in the test page navigation.

I had the math wrong in #2818.  It is correct if the number of problems
does not evenly divide the number of problems per page, but if it does
then the modulus returns 0.  In that case it should also use the number
of problems per page.

Author: drgrice1

templates/ContentGenerator/GatewayQuiz.html.ep

@@ -459,7 +459,9 @@
 			% end
 			% for my $i (1 .. $numPages) {
 				% content_for 'gw-navigation-pages' => begin
-					<td colspan="<%= $i == $numPages ? (@$problem_numbers % $numProbPerPage) : $numProbPerPage %>"
+					<td colspan="<%= $i == $numPages && (@$problem_numbers % $numProbPerPage)
+						? (@$problem_numbers % $numProbPerPage)
+						: $numProbPerPage %>"
 						class="<%= $i == $pageNumber ? 'page active' : 'page' %>">
 						% if ($i == $pageNumber) {
 							<%= $i =%>