Hideable Scheduled Shows tab

Makes the first tab remoeable and the tracks page be full width after removing the last tab. You can press the "Dashboard" link to open it back up again.

airtime_mvc/public/js/airtime/showbuilder/main_builder.js

@@ -187,6 +187,12 @@ AIRTIME = (function(AIRTIME) {
         //Highlight the media type selector we're currently on.
         highlightMediaTypeSelector();
 
+        // always re-show builder if dashboard button was clicked
+        $('.media_type_selector:first').on('click', function() {
+            $builder.show();
+            AIRTIME.tabs.openScheduleTab();
+        });
+
         /*
          * Icon hover states for search.
          */