Implemented the second round of the toResponse normalisationf for all classes

ref #67

src/models/entities/Runner.ts

@@ -1,5 +1,6 @@
 import { IsInt, IsNotEmpty } from "class-validator";
 import { ChildEntity, ManyToOne, OneToMany } from "typeorm";
+import { ResponseRunner } from '../responses/ResponseRunner';
 import { DistanceDonation } from "./DistanceDonation";
 import { Participant } from "./Participant";
 import { RunnerCard } from "./RunnerCard";
@@ -66,4 +67,11 @@ export class Runner extends Participant {
   public get distanceDonationAmount(): number {
     return this.distanceDonations.reduce((sum, current) => sum + current.amountPerDistance, 0) * this.distance;
   }
+
+  /**
+   * Turns this entity into it's response class.
+   */
+  public toResponse(): ResponseRunner {
+    return new ResponseRunner(this);
+  }
 }