title: Laravel Find Not working with custom primary key
body: <p>I am stuck with a situation where i coudn't update my records using Eloquent in Laravel 5.5 using custom primary key.<br>
  Here is what i tried :-<br>
  In my Model.php i have,</p>
  
  <p><code>protected $primarykey = 'custom_primary_key';</code>     </p>
  
  <p>my migrations looks like :-<br>
  <code>$table-&gt;increments('custom_primary_key');</code>  </p>
  
  <p>in my controller,i have :-</p>
  
  <pre><code>Model::find(custom_primary_key);
  </code></pre>
  
  <p>but when i tries to find a record using <code>find()</code> in my controller, it gives</p>
  
  <pre><code>Column not found: 1054 Unknown column 'table.id' in 'where clause' (SQL: select * from `table` where `table`.`id` = 1 and `table`.`deleted_at` is null limit 1)"   
  </code></pre>
  
  <p>table also contains a column with custom primary key and there is no column named <code>id</code>.</p>
  
  <p>It doesnt recognize the cutom primary key. Where can i be missing something ?</p>