Feature: View a contact's previous conversation (#422)

* Add API to fetch conversations of a contact

* Add conversation list in sidebar

app/javascript/dashboard/api/contacts.js

@@ -1,9 +1,14 @@
+/* global axios */
 import ApiClient from './ApiClient';
 
 class ContactAPI extends ApiClient {
   constructor() {
     super('contacts');
   }
+
+  getConversations(contactId) {
+    return axios.get(`${this.url}/${contactId}/conversations`);
+  }
 }
 
 export default new ContactAPI();

app/javascript/dashboard/api/specs/contacts.spec.js

@@ -0,0 +1,14 @@
+import agents from '../contacts';
+import ApiClient from '../ApiClient';
+
+describe('#ContactsAPI', () => {
+  it('creates correct instance', () => {
+    expect(agents).toBeInstanceOf(ApiClient);
+    expect(agents).toHaveProperty('get');
+    expect(agents).toHaveProperty('show');
+    expect(agents).toHaveProperty('create');
+    expect(agents).toHaveProperty('update');
+    expect(agents).toHaveProperty('delete');
+    expect(agents).toHaveProperty('getConversations');
+  });
+});