improved code styles #158 (#172)

* use php-cs-fixer instead of phpcodesniffer
* updated scrutinizer config
* adjusted code yules to all files
* updated CONTRIBUTING guidelines

tests/Controller/TimesheetControllerTest.php

@@ -9,16 +9,12 @@
 
 namespace App\Tests\Controller;
 
-use App\DataFixtures\AppFixtures;
-use App\Entity\User;
-
 /**
  * @coversDefaultClass \App\Controller\TimesheetController
  * @group integration
  */
 class TimesheetControllerTest extends ControllerBaseTest
 {
-
     public function testIsSecure()
     {
         $this->assertUrlIsSecured('/timesheet/');