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

* Add API to fetch conversations of a contact

* Add conversation list in sidebar

app/javascript/dashboard/store/index.js

@@ -7,6 +7,7 @@ import billing from './modules/billing';
 import cannedResponse from './modules/cannedResponse';
 import Channel from './modules/channels';
 import contacts from './modules/contacts';
+import contactConversations from './modules/contactConversations';
 import conversationMetadata from './modules/conversationMetadata';
 import conversations from './modules/conversations';
 import inboxes from './modules/inboxes';
@@ -22,6 +23,7 @@ export default new Vuex.Store({
     cannedResponse,
     Channel,
     contacts,
+    contactConversations,
     conversationMetadata,
     conversations,
     inboxes,