updates progress bar accuracy

The progress bar now accounts for live coders that have opted for
"finish later"

Address part of issue #63

test/fixtures/answers.yml

@@ -373,8 +373,9 @@ juan9:
 juan10:
   candidate: juan
   question: fed10
-  answer:
+  answer: 'wibbly wobbly, timey wimey'
   saved: 1
   submitted: true
   created_at: <%= DateTime.now() - 38.hours - 40.minutes %>
   updated_at: <%= DateTime.now() - 38.hours - 20.minutes %>
+