Update stories to not use moment directly

ng/src/web/stories/chart/line.js

@@ -22,10 +22,10 @@
  */
 import React from 'react';
 
-import moment from 'moment';
-
 import {longDate} from 'gmp/locale/date';
 
+import date from 'gmp/models/date';
+
 import {storiesOf} from '@storybook/react';
 import {action} from '@storybook/addon-actions';
 
@@ -54,7 +54,6 @@ const linedata = [{
 },
 ];
 
-
 storiesOf('Chart/Line', module)
   .add('default', () => {
     return (
@@ -125,7 +124,7 @@ storiesOf('Chart/Line', module)
     );
   })
   .add('timeline', () => {
-    const start = moment().subtract(2, 'year');
+    const start = date().subtract(2, 'year');
     const dates = [
       start,
       start.clone().add(1, 'year'),

ng/src/web/stories/chart/schedule.js

@@ -22,7 +22,7 @@
  */
 import React from 'react';
 
-import moment from 'moment';
+import date from 'gmp/models/date';
 
 import {storiesOf} from '@storybook/react';
 
@@ -35,30 +35,30 @@ const SEVEN_HOURS = 60 * 60 * 7;
 
 const data = [{
   label: 'Foo',
-  start: moment().add(1, 'day'),
+  start: date().add(1, 'day'),
   duration: ONE_DAY,
 }, {
   label: 'Bar',
-  start: moment().add(2, 'day'),
+  start: date().add(2, 'day'),
   period: ONE_WEEK,
 }, {
   label: 'Lorem',
-  start: moment().add(4, 'hours'),
+  start: date().add(4, 'hours'),
   period: TWO_DAYS,
   periods: 4,
   duration: ONE_DAY,
 }, {
   label: 'Ipsum',
-  start: moment().add(2, 'day').add(4, 'hours'),
+  start: date().add(2, 'day').add(4, 'hours'),
   period: SEVEN_HOURS,
 }, {
   label: 'Dolor',
-  start: moment().add(3, 'day').add(4, 'hours'),
+  start: date().add(3, 'day').add(4, 'hours'),
   period: ONE_WEEK,
   periods: 2,
 }, {
   label: 'Sit',
-  start: moment().add(1, 'day').add(4, 'hours'),
+  start: date().add(1, 'day').add(4, 'hours'),
   period: 0,
   periods: 0,
   periodMonth: 2,

ng/src/web/stories/datepicker/index.js

@@ -23,16 +23,17 @@
 
 import React from 'react';
 import glamorous from 'glamorous';
-import moment from 'moment';
+
+import date from 'gmp/models/date';
 
 import {storiesOf} from '@storybook/react';
 
 import PropTypes from '../../utils/proptypes.js';
 
 import DatePicker from 'web/components/form/datepicker.js';
 
-const today = moment();
-const testdate = moment('2018-10-10');
+const today = date();
+const testdate = date('2018-10-10');
 
 class ControlledDatePicker extends React.Component {