Added address validity check

ref #105

src/models/entities/Address.ts

@@ -57,9 +57,10 @@ export class Address {
   country: string;
 
   /**
-   * Turns this entity into it's response class.
+   * Checks if this is a valid address
    */
-  public toResponse() {
-    return new Error("NotImplemented");
+  public get isValidAddress(): Boolean {
+    if (!this.address1 || !this.city || !this.country || !this.postalcode) { return false; }
+    return true;
   }
 }