NullPointerException org.scribe.model.Response

by calling method Response.getBody() if the Body of the Response is null.
Bugfix would be:

``` java
package org.scribe.model;
//....
  private String parseBodyContents()
  {
    try{
      body = StreamUtils.getStreamContents(getStream());
      return body;
    }catch(Exception e){
      return "";
    }
  }
```
