Bug fix for unused Node::all columns argument & unit test

Fix from here: etrepat#181

Author: gazsp

src/Baum/Node.php

@@ -364,7 +364,7 @@ public static function all($columns = array('*')) {
 
     return $instance->newQuery()
                     ->orderBy($instance->getQualifiedOrderColumnName())
-                    ->get();
+                    ->get($columns);
   }
 
   /**

tests/suite/Category/CategoryHierarchyTest.php

@@ -9,6 +9,13 @@ public function testAllStatic() {
     $this->assertEquals($results, $expected);
   }
 
+  public function testAllStaticSomeColumns() {
+    $results = Category::all(['id','name'])->toArray();
+    $expected = Category::query()->select(['id', 'name'])->orderBy('lft')->get()->toArray();
+
+    $this->assertEquals($results, $expected);
+  }
+
   public function testAllStaticWithCustomOrder() {
     $results = OrderedCategory::all();
     $expected = OrderedCategory::query()->orderBy('name')->get();