title: Errors in laravel-5 configuration
body: <p>I got multiple errors while configurating project on laravel (downloading existing project using git and composer). Errors are shown after logging to the main page of project, login panel is displayed properly.</p>
  
  <p>(1/4) FatalThrowableError</p>
  
  <blockquote>
    <p>Parse error: syntax error, unexpected 'const' (T_CONST), expecting
    variable (T_VARIABLE)
        in PDOStatement.php line 40</p>
  </blockquote>
  
  <p>(2/4) PDOException</p>
  
  <blockquote>
    <p>SQLSTATE[HY000]: General error: PDO::ATTR_STATEMENT_CLASS requires
    format array(classname, array(ctor_args)); the classname must be a
    string specifying an existing class
        in PDOConnection.php line 47</p>
  </blockquote>
  
  <p>(3/4) PDOException</p>
  
  <blockquote>
    <p>SQLSTATE[HY000]: General error: PDO::ATTR_STATEMENT_CLASS requires 
        format array(classname, array(ctor_args)); the classname must be a string specifying an existing class</p>
    
    <p>in PDOConnection.php line 50</p>
  </blockquote>
  
  <p>(4/4) QueryException</p>
  
  <blockquote>
    <p>SQLSTATE[HY000]: General error: PDO::ATTR_STATEMENT_CLASS requires 
        format array(classname, array(ctor_args)); the classname must be a string specifying an existing class (SQL: select * from "users" where
    "email" = [my_email] limit 1)
        in Connection.php line 647</p>
  </blockquote>
  
  <p>im using php7.1, postgres, apache2 server, doctrine/dbal(2.6.3)</p>
  
  <p>migrate database using php artisan</p>