Refactor workbook table fields
Refactor workbook table fields

Remove description field since there's no such attribute on
workbook, also add created and updated fields.

Change-Id: I0805402c15dfef9d0400f05b525c83f2090584c4
Closes-Bug: #1471777

openstack/mistral-dashboard,openstack/mistral-dashboard,openstack/mistral-dashboard