Activate ui-select only when user inputs 2+ chars in search box

This should help with performance, as per
angular-ui/ui-select#88 (comment)

Author: danii-nebot

src/js/components/search-form.component.js

@@ -3,6 +3,7 @@ class SearchFormCtrl {
     'ngInject';
 
     this._$state = $state;
+    this.limitSeriesSearch = 0;
 
     this.series = [
       { title: 'A Song of Ice and Fire', author: 'George RR Martin', keywords: 'Game of Thrones', slug:'a-song-of-ice-and-fire'},
@@ -11,6 +12,11 @@ class SearchFormCtrl {
     ];
   };
 
+  // https://github.com/angular-ui/ui-select/issues/88#issuecomment-179916133
+  checkSearch(search) {
+    this.limitSeriesSearch = (search.length > 1)? 9999 : 0;
+  }
+
   submit() {
     if(this.selectedItem) {
       this._$state.go('app.graph', { slug: this.selectedItem.slug });

src/js/components/search-form.html

@@ -1,16 +1,19 @@
 <ng-transclude></ng-transclude>
-
-<!-- classes ui-select-match & ui-select-choices required to fix https://github.com/angular-ui/ui-select/issues/1325 -->
-<ui-select ng-model="$ctrl.selectedItem" theme="bootstrap">
-  <ui-select-match class="ui-select-match">
-      <span ng-bind="$select.selected.title"></span>
-  </ui-select-match>
-  <ui-select-choices class="ui-select-choices" repeat="book in ($ctrl.series | filter: $select.search) track by book.slug">
-      <span ng-bind="::book.title"></span>
-  </ui-select-choices>
-</ui-select>
-<span class="input-group-btn">
-  <button class="btn btn-s btn-primary pull-xs-right" type="submit"
-          ng-class="{disabled: !$ctrl.selectedItem }"
-          ng-click="$ctrl.submit()">Go!</button>
-</span>
+<div class="input-group">
+  <!-- classes ui-select-match & ui-select-choices required to fix https://github.com/angular-ui/ui-select/issues/1325 -->
+  <ui-select ng-model="$ctrl.selectedItem" reset-search-input="false">
+    <ui-select-match class="ui-select-match" placeholder="Type your favourite sci-fi series or author...">
+        <span ng-bind="$select.selected.title"></span>
+    </ui-select-match>
+    <ui-select-choices class="ui-select-choices" refresh="$ctrl.checkSearch($select.search)" refresh-delay="50"
+      repeat="book in ($ctrl.series | filter: $select.search | limitTo: $ctrl.limitSeriesSearch) track by book.slug">
+        <span ng-bind="book.title"></span>
+        <small>by {{ book.author }}</small>
+    </ui-select-choices>
+  </ui-select>
+  <span class="input-group-btn">
+    <button class="btn btn-s btn-primary pull-xs-right" type="submit"
+            ng-class="{disabled: !$ctrl.selectedItem }"
+            ng-click="$ctrl.submit()">Go!</button>
+  </span>
+</div>