Implemented the second round of the toResponse normalisationf for all classes

ref #67

src/models/entities/Donor.ts

@@ -1,5 +1,6 @@
 import { IsBoolean } from "class-validator";
 import { ChildEntity, Column, OneToMany } from "typeorm";
+import { ResponseDonor } from '../responses/ResponseDonor';
 import { Donation } from './Donation';
 import { Participant } from "./Participant";
 
@@ -22,4 +23,11 @@ export class Donor extends Participant {
  */
   @OneToMany(() => Donation, donation => donation.donor, { nullable: true })
   donations: Donation[];
+
+  /**
+   * Turns this entity into it's response class.
+   */
+  public toResponse(): ResponseDonor {
+    return new ResponseDonor(this);
+  }
 }