All api calls from tests use same chaiHttp implementation

Removes a list of fetch alternatives after being replaced by chaiHttp:
 - request
 - request-promise
 - supertest
 - supertest-as-promised

tests/system/asADeveloperIWantTheServerToRegister.js

@@ -1,17 +1,24 @@
 const assert = require("assert");
-const request = require("supertest-as-promised");
-const app = require("../../src/webserver/app");
+const chai = require("chai");
+const chaiHttp = require("chai-http");
+
+const server = require("../../src/webserver/server");
 const resetDatabase = require("../helpers/resetDatabase");
 
+chai.use(chaiHttp);
+
 describe("As a user I want to register", () => {
   beforeEach(() => resetDatabase());
 
-  it("should return 200 and a message indicating success", () =>
-    request(app)
+  it("should return 200 and a message indicating success", done => {
+    chai
+      .request(server)
       .post("/api/v1/user")
       .send({ username: "test", email: "test@gmail.com", password: "password" })
-      .expect(200)
-      .then(response =>
-        assert.equal(response.body.message, "Welcome to Seasoned!")
-      ));
+      .end((error, response) => {
+        assert.equal(response?.status, 200);
+        assert.equal(response?.body?.message, "Welcome to Seasoned!");
+        done();
+      });
+  });
 });