Redesign splashpage program section & split out partials

app/views/conferences/_tracks.haml

@@ -0,0 +1,17 @@
+.row
+  .col-md-12
+    %h3.text-center
+      Tracks
+.row.row-centered
+  - @conference.confirmed_tracks.to_a.sort_by!(&:name).each do |track|
+    .col-md-3.col-sm-3.col-centered.col-top.track
+      .thumbnail
+        .caption
+          %h3.text-center
+            = track.name
+          %p.text-center
+            - if track.start_date && track.end_date
+              = date_string(track.start_date, track.end_date)
+            - if track.room
+              In #{track.room.name}
+          = markdown truncate(track.description, length: 200, separator: ' ')