Improve card and list sortable drag

Use a custom build of jquery-ui with only the plugins we need (instead
of including everything).

Fix a tricky bug of conflict between Blaze reactive updates and
jquery-ui (which caused cards to sometimes disappear).

client/components/boards/boardBody.js

@@ -72,10 +72,10 @@ BlazeComponent.extendComponent({
 
     self.$(lists).sortable({
       tolerance: 'pointer',
-      appendTo: '.js-lists',
       helper: 'clone',
       items: '.js-list:not(.js-list-composer)',
       placeholder: 'list placeholder',
+      distance: 7,
       start: function(evt, ui) {
         ui.placeholder.height(ui.helper.height());
         Popup.close();