Add initial e2e testing with cypress

Add e2e tests with cypress using `vue add e2e-cypress`.

Vue CLI does not support creating typescript tests at this moment
(vuejs/vue-cli#1350).

tests/e2e/specs/initialization.spec.js

@@ -0,0 +1,39 @@
+describe('application is initialized as expected', () => {
+  it('loads title as expected', () => {
+    // act
+    cy.visit('/');
+    // assert
+    cy.contains('h1', 'privacy.sexy')
+  });
+  it('there are no console.error output', () => {
+    // act
+    // https://docs.cypress.io/faq/questions/using-cypress-faq#How-do-I-spy-on-console-log
+    cy.visit('/', {
+      onBeforeLoad(win) {
+        cy.stub(win.console, 'error').as('consoleError')
+      }
+    });
+    // assert
+    cy.get('@consoleError').should('have.not.been.called');
+  });
+  it('there are no console.warn output', () => {
+    // act
+    cy.visit('/', {
+      onBeforeLoad(win) {
+        cy.stub(win.console, 'warn').as('consoleWarn')
+      }
+    });
+    // assert
+    cy.get('@consoleWarn').should('have.not.been.called');
+  });
+  it('there are no console.log output', () => {
+    // act
+    cy.visit('/', {
+      onBeforeLoad(win) {
+        cy.stub(win.console, 'log').as('consoleLog')
+      }
+    });
+    // assert
+    cy.get('@consoleLog').should('have.not.been.called');
+  });
+});