added rounding rules and hourly rates factor #112 (#128)

* added unit tests and documentation #112
* fixed DashboardController
* added CONTRIBUTION guidelines
* fixed license year

src/Kernel.php

@@ -1,9 +1,17 @@
 <?php
 
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace App;
 
 use App\DependencyInjection\AppExtension;
 use App\DependencyInjection\Compiler\DoctrineCompilerPass;
+use App\Timesheet\CalculatorInterface;
 use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
 use Symfony\Component\Config\Loader\LoaderInterface;
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
@@ -27,6 +35,11 @@ class Kernel extends BaseKernel
         return $this->getProjectDir().'/var/log';
     }
 
+    protected function build(ContainerBuilder $container)
+    {
+        $container->registerForAutoconfiguration(CalculatorInterface::class)->addTag('timesheet.calculator');
+    }
+
     public function registerBundles()
     {
         $contents = require $this->getProjectDir().'/config/bundles.php';