Added services

This commit moves most controller logic onto Services. Services are part of the Service-Repository pattern. The models act as repositories.

Services are easily testable and are needed for the upcoming API, in order to avoid duplicated code and to maintain a single source of "truth".

 The User, Vacancy and Vote controllers still need their logic moved onto services.

app/Services/MeetingNoteService.php

@@ -0,0 +1,36 @@
+<?php
+
+
+namespace App\Services;
+
+
+use App\Application;
+use App\Exceptions\InvalidAppointmentException;
+
+class MeetingNoteService
+{
+    /**
+     * Adds meeting notes to an application.
+     *
+     * @param Application $application
+     * @param $noteText
+     * @return bool
+     * @throws InvalidAppointmentException Thrown when an application doesn't have an appointment to save notes to
+     */
+    public function addToApplication(Application $application, $noteText): bool {
+
+        if (! is_null($application)) {
+            $application->load('appointment');
+
+            $application->appointment->meetingNotes = $noteText;
+            $application->appointment->save();
+
+            return true;
+
+        } else {
+            throw new InvalidAppointmentException('There\'s no appointment to save notes to!');
+        }
+
+    }
+
+}