Mccalluc/search facet labels (#1976)

* Basic machinery

* A litte style. Case-insensitive matching.

refinery/ui/source/js/user-file-browser/partials/user-file-browser-filters.html

@@ -2,6 +2,9 @@
   <div class="panel-group data-set-filters" id="attribute-filter"
     role="tablist"
     aria-multiselectable="true">
+    <div class="refinery-subheader m-t-1">
+      <input ng-model="search" ng-init="search = ''" style="width: 100%;" placeholder="search...">
+    </div>
     <div
       ng-repeat="(attribute, attributeObj) in $ctrl.attributeFilters track by $index"
       ng-init="attributeIndex = $index">
@@ -20,7 +23,7 @@ <h4 class="panel-title" ng-click="$ctrl.togglePanel(attribute)">
         aria-labelledby="{{ attribute }}">
         <div class="panel-body">
           <div ng-repeat="field in attributeObj.facetObj track by $index">
-            <div class="checkbox container">
+            <div ng-show="field.name.toLowerCase().includes(search.toLowerCase())" class="checkbox container">
                 <div class="row">
                   <div class="col-xs-1">
                     <input