Fix charset on /data controller

The global http settings in the application.yml seem to not work with
manually defined media types.

Author: Brutus5000

src/main/java/com/faforever/api/achievements/AchievementsController.java

@@ -25,7 +25,6 @@
 @RequiredArgsConstructor
 public class AchievementsController {
 
-  private static final String JSON_API_MEDIA_TYPE = "application/vnd.api+json";
   private final AchievementService achievementService;
   private AtomicInteger nextUpdateId = new AtomicInteger();
 

src/main/java/com/faforever/api/data/JsonApiMediaType.java

@@ -1,6 +1,6 @@
 package com.faforever.api.data;
 
 public class JsonApiMediaType {
-  public static final String JSON_API_MEDIA_TYPE = "application/vnd.api+json";
-  public static final String JSON_API_PATCH_MEDIA_TYPE = "application/vnd.api+json;ext=jsonpatch";
+  public static final String JSON_API_MEDIA_TYPE = "application/vnd.api+json;charset=utf-8";
+  public static final String JSON_API_PATCH_MEDIA_TYPE = "application/vnd.api+json;ext=jsonpatch;charset=utf-8";
 }

src/main/java/com/faforever/api/event/EventsController.java

@@ -26,7 +26,6 @@
 @RequiredArgsConstructor
 public class EventsController {
 
-  private static final String JSON_API_MEDIA_TYPE = "application/vnd.api+json";
   private final EventsService eventsService;
 
   @ApiOperation(value = "Updates the state and progress of one or multiple events.")

src/main/java/com/faforever/api/voting/VotingController.java

@@ -15,7 +15,6 @@
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;
 
-import javax.inject.Inject;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
@@ -26,7 +25,6 @@
 @RequiredArgsConstructor
 public class VotingController {
   static final String PATH = "/voting";
-  private static final String JSON_API_MEDIA_TYPE = "application/vnd.api+json";
   private final VotingService votingService;
   private final PlayerService playerService;