title: Remove child node using lift-json
body: <p>I'm using lift-json 2.3 and Scala 2.8.1 to manipulate json documnts.  In the following document I want to remove a single node.</p>
  
  <pre><code>{
    "units": {
      "1": {
        "id":"1", 
        "name":"one", 
        "tenants": {
          "1" : {
            "id": "1",
            "name":"x"
          },
          "2" : {        // node I want removed
            "id": "2",
            "name":"y"
          }
        }
      }
      "2": {
        "id":"2", 
        "name":"two", 
        "tenants": {
          "1" : {
            "id": "1",
            "name":"x"
          },
          "2" : {
            "id": "2",
            "name":"z"
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>I know I can remove nodes with the remove method:</p>
  
  <pre><code>val js2 = js \ "units" \ "1" \ "tenants" remove {
      case JField(id, _) =&gt; id == "2"
      case _ =&gt; false
  }
  </code></pre>
  
  <p>But, I need the entire document changed.</p>