[Common UI] Generalize ToggleController

Add a general-purpose ToggleController for things that
need to expand and contract. WTD-574.

platform/commonUI/general/res/templates/containers/accordion.html

@@ -1,9 +1,9 @@
-<div class="accordion" ng-controller="AccordionController as accordion">
-    <div class="accordion-head" ng-click="accordion.toggle()">
+<div class="accordion" ng-controller="ToggleController as toggle">
+    <div class="accordion-head" ng-click="toggle.toggle()">
         {{container.title}}
     </div>
     <div class="accordion-contents"
-         ng-show="accordion.expanded()"
+         ng-show="toggle.isActive()"
          style="height: 180px;"
          ng-transclude>
     </div>

platform/commonUI/general/res/templates/tree-item.html

@@ -1,7 +1,9 @@
-<span ng-controller="TreeNodeController">
-<span class="tree-item menus-to-left">
-	<span class='ui-symbol view-control' ng-click="toggle()" ng-if="model.composition !== undefined">
-        {{node.expanded ? "v" : ">"}}
+<span ng-controller="ToggleController as toggle">
+<span class="tree-item menus-to-left" ng-controller="TreeNodeController">
+	<span class='ui-symbol view-control'
+          ng-click="toggle.toggle()"
+          ng-if="model.composition !== undefined">
+        {{toggle.isActive() ? "v" : ">"}}
     </span>
     <mct-representation key="'label'"
                         mct-object="domainObject"
@@ -10,7 +12,9 @@
                         ng-class="{selected: node.isSelected}">
     </mct-representation>
 </span>
-<span class="tree-item-subtree" ng-show="node.expanded" ng-if="model.composition !== undefined">
+<span class="tree-item-subtree"
+      ng-show="toggle.isActive()"
+      ng-if="model.composition !== undefined">
     <mct-representation key="'tree'"
                         parameters="parameters"
                         mct-object="node.domainObject">