Add localforage, basic cache service

app/services/browser-cache.js

@@ -0,0 +1,25 @@
+import Service from '@ember/service';
+import * as localforage from 'localforage';
+
+function createStore(name) {
+  return localforage.createInstance({ name: `kredits:${name}` });
+}
+
+export default class BrowserCacheService extends Service {
+
+  constructor() {
+    super(...arguments);
+    this.stores = {
+      contributors:  createStore('contributors'),
+      contributions: createStore('contributions')
+    }
+  }
+
+  get contributors() {
+    return this.stores.contributors;
+  }
+
+  get contributions() {
+    return this.stores.contributions;
+  }
+}

app/services/kredits.js

@@ -230,7 +230,7 @@ export default Service.extend({
   },
 
   getContributions () {
-    return this.kredits.Contribution.all({page: {size: 200}})
+    return this.kredits.Contribution.all({page: {size: 30}})
       .then(contributions => {
         return contributions.map(contribution => {
           contribution.contributor = this.contributors.findBy('id', contribution.contributorId.toString());