title: Laravel migration fails multiple primary keys
body: <p>I am trying to create a Migration in Laravel but it fails saying I got multiple primary keys.</p>
  
  <pre class="lang-php prettyprint-override"><code>public function up()
  {
      Schema::create('spins', function (Blueprint $table) {
          $table-&gt;integer('rid', true, true);
          $table-&gt;bigInteger('pid');
          $table-&gt;integer('result');
          $table-&gt;integer('bet');
          $table-&gt;timestamps();
          $table-&gt;primary(array('rid', 'pid'));
      });
  }
  </code></pre>
  
  <p>The error:</p>
  
  <pre><code>SQLSTATE[42000]: Syntax error or access violation: 1068 Multipleprimary key defined 
  (SQL: alter table `spins` add primary key `spins_rid_pid_primary` (`rid`, `pid`))      
  </code></pre>