title: Laravel get nested relation value
body: <p>Is exist a possibility to easy get relation value in Laravel 5?
  Here an example of what i need:</p>
  
  <p>I have model <code>Book</code> and i have <code>author</code> relation to model <code>Author</code>. <code>Author</code> also have relation <code>country</code> to model <code>Country</code>. I need to show on book page country name of Author. I can easy wrote:</p>
  
  <pre><code>echo $model-&gt;author-&gt;country-&gt;name
  </code></pre>
  
  <p>But what if a author of book not provided or we don't know author coutry? I will got a notice.</p>
  
  <p>So I need to add additional checkings:</p>
  
  <pre><code>if ($model-&gt;author &amp;&amp; $model-&gt;author-&gt;country) echo $model-&gt;author-&gt;country-&gt;name
  </code></pre>
  
  <p>Maybe exists some method in laravel, which simplify getting a value?
  Maybe something like <code>SomeHelperClass::getValue($model, 'author.country.name')</code>, so if some part of the chain is <code>null</code>, then method also returns <code>null</code>. Thanks.</p>