WIP Generic data handling and caching

Add basic support for reimbursements via new, generic data handling
functions.

app/models/reimbursement.js

@@ -0,0 +1,48 @@
+import EmberObject, { computed } from '@ember/object';
+import { isEmpty, isPresent } from '@ember/utils';
+import moment from 'moment';
+
+export default EmberObject.extend({
+
+  // Contract
+  id: null,
+  contributorId: null,
+  token: null,
+  amount: null,
+  confirmedAt: null,
+  vetoed: null,
+  ipfsHash: null,
+
+  // contributor model instance
+  contributor: null,
+
+  // TODO contributor who submitted the reimbursement
+  // recordedBy: null,
+
+  // IPFS
+  expenses: null, // Array of expense objects
+
+  pendingTx: null,
+
+  init () {
+    this._super(...arguments);
+    if (isEmpty(this.details)) this.set('details', {});
+  },
+
+  iso8601Date: computed('date', 'time', function() {
+    return this.time ? `${this.date}T${this.time}` : this.date;
+  }),
+
+  jsDate: computed('iso8601Date', function() {
+    return moment(this.iso8601Date).toDate();
+  }),
+
+  hasPendingChanges: computed('pendingTx', function() {
+    return isPresent(this.pendingTx);
+  }),
+
+  serialize () {
+    return JSON.stringify(this);
+  }
+
+});