Fewer queries for for Conference#show

Reduces SQL wait times by >90% on splash pages.

app/views/conferences/_call_for_tracks.html.haml

@@ -12,19 +12,17 @@
   .row
     .col-md-6.col-md-offset-3.col-sm-10.col-sm-offset-1
       %p
-        The submission period for track requests has begun
+        The submission period for track requests is open
         %em.notranslate
-          = @conference.program.cfps.for_tracks.start_date.strftime('%A, %B %-d. %Y')
-        and closes
-        %em.notranslate
-          = @conference.program.cfps.for_tracks.end_date.strftime('%A, %B %-d. %Y.')
-        - if @conference.program.cfps.for_tracks.try(:open?)
-          That means you have only
-          %b.notranslate= pluralize(@conference.program.cfps.for_tracks.remaining_days, 'day')
+          = "#{date_string(@conference.call_for_tracks.start_date,
+            @conference.call_for_tracks.end_date)}."
+        %b
+          You have
+          = pluralize(@conference.call_for_tracks.remaining_days, 'day')
           left!
-        - else
-          The submission period for track requests is closed.
   .row
     .col-md-12.text-center
       %p.cta-button
-        = link_to "Submit your request for track", conference_program_tracks_path(@conference.short_title), class: 'btn btn-success btn-lg text-center'
+        = link_to("Submit your request for track",
+          conference_program_tracks_path(@conference.short_title),
+          class: 'btn btn-success btn-lg text-center')