Journal UI Improvements

Closes #14 

In this Pull Request:
 - Minor CSS fixes including:
   - Trial balance modal footer columns aligned
   - Trial balance modal body removed 3px whitespace error on above `<tbody>`
   - class: extend now applies to `<main>` element
- updateItem(id, args) fix:  `id` field now defaults to `uuid` if `id` not found. (eliminates a class of errors).
- Critical fix to date input in posting_journal.  Now behaves as expected
- added SlickGrid sort direction images
- Profit Center and Cost Centers added with editors.