(js) Replace vs-repeat by md-virtual-repeat

There're some issues with mdVirtualRepeat that required some changes to
our app:

1. Having multiple directives with md-virtual-repeat doesn't work well.
That why I added a dedicated div for the md-virtual-repeat directive.
2. ui-sref-active doesn't work well for child nodes of the
md-virtual-repeat element. The class was applied repetitively to a
visible child. I now save which message or card is selected and use the
ng-class directive to highlight the selected list item.

UI/WebServerResources/scss/components/virtualRepeat/_extends.scss

@@ -0,0 +1,2 @@
+/*! virtualRepeat/_extends.scss - */
+@import '../../../angular-material/src/components/virtualRepeat/virtualRepeater.scss';

UI/WebServerResources/scss/components/virtualRepeat/virtualRepeat.scss

@@ -0,0 +1,9 @@
+/// virtualRepeater.scss -*- Mode: scss; indent-tabs-mode: nil; basic-offset: 2 -*-
+@import 'extends';
+
+// Override some md styles
+.md-virtual-repeat-container {
+  .md-virtual-repeat-offsetter {
+    right: 0; // no need to keep space for the scrollbar
+  }
+}