Added cypress test to test embedded mode

cypress.json

@@ -1,5 +1,6 @@
 {
   "viewportWidth": 1280,
   "viewportHeight": 1024,
+  "chromeWebSecurity": false,
   "baseUrl": "http://localhost:3000/#"
 }

cypress/integration/embedded.spec.js

@@ -0,0 +1,11 @@
+describe('Embedded mode', () => {
+  it('shows data', () => {
+    const url = 'https://pewu.github.io/topola-embedded/#' + Cypress.config('baseUrl');
+    cy.visit(url);
+    cy.get('iframe')
+    .its('0.contentDocument.body').should('not.be.empty')
+      .then(cy.wrap)
+      .find('#root')
+      .contains('Bonifacy');
+  });
+});