Fix annotation privacy note moving depending on which item was selected

Due to the existence of a 'p + p' selector in app.css, the <p>
element containing the 'This annotation is visible only to you'
label was displayed at a different vertical position to
the alternative labels.

Use ng-if rather than ng-show to remove the non-visible
labels so that the rendered <p> is always the first <p> child
of its parent and therefore always rendered at the same position.

h/templates/client/annotation.html

@@ -119,18 +119,17 @@
 
   <footer class="annotation-footer">
     <div class="small" ng-if="vm.editing">
-      <p ng-show="vm.isPrivate()">
+      <p ng-if="vm.isPrivate()">
         <i class="h-icon-lock"></i>
         This annotation will be visible only to you.
       </p>
-      <p ng-show="vm.isShared() && vm.group().public">
+      <p ng-if="vm.isShared() && vm.group().public">
         <i class="h-icon-public"></i>
         This annotation will be visible to everyone.
       </p>
-      <p ng-show="vm.isShared() && !vm.group().public">
+      <p ng-if="vm.isShared() && !vm.group().public">
         <i class="h-icon-group"></i>
-        This annotation will be visible to everyone in the
-        <strong ng-bind="vm.group().name"></strong> group.
+        This annotation will be visible to everyone in <strong ng-bind="vm.group().name"></strong>.
       </p>
     </div>