Add mock client for Contentful

Contentful provide a client via the contentful npm package and they
provide some boilerplate code. This commit aims to mirror the client's
interface (only one method at the moment, for Pride events) and return
data from the mock server.

https://github.com/contentful/contentful.js

Add `browser: true` to eslintrc file, otherwise it complains that the `fetch`
method in MockClient has not been defined.
See eslint/eslint#4015

.eslintrc

@@ -1,7 +1,8 @@
 {
   "env": {
     "jest": true,
-    "node": true
+    "node": true,
+    "browser": true,
   },
   "extends": ["airbnb", "prettier"],
   "parserOptions": {

App.js

@@ -1,7 +1,9 @@
 import React, { Component } from "react";
 import { ActivityIndicator, FlatList, Text, View } from "react-native";
+import MockClient from "./MockClient";
 
-const API_URL = "http://192.168.1.4:3000/events";
+const client = MockClient; // Swap this out for the Contentful client in prod
+const EVENTS_CONTENT_TYPE_SYS_ID = 123; // This will eventually be dynamic, based on the id in Contentful
 
 export default class App extends Component {
   constructor(props) {
@@ -12,16 +14,17 @@ export default class App extends Component {
   }
 
   componentDidMount() {
-    return fetch(API_URL)
-      .then(response => response.json())
+    return client
+      .getEntries({
+        content_type: EVENTS_CONTENT_TYPE_SYS_ID
+      })
       .then(responseJson => {
-        console.log(responseJson);
         this.setState(
           {
             isLoading: false,
             dataSource: responseJson
           },
-          function() {
+          () => {
             // do something with new state
           }
         );

MockClient.js

@@ -0,0 +1,12 @@
+const API_URL = "http://192.168.1.4:3000";
+const SYS_ID_TO_URL_MAPPINGS = {
+  123: "/events"
+};
+
+export default class MockClient {
+  static getEntries(contentTypes) {
+    const contentTypeUrl = SYS_ID_TO_URL_MAPPINGS[contentTypes.content_type];
+
+    return fetch(API_URL + contentTypeUrl).then(response => response.json());
+  }
+}