Sortable Table using Polymer Web Components

# <sortable-table> Features

There are many capable Javascript grids, this one aims to have all the same features plus:

- leverage native browser support for `template` to be fully customizable, and
- be declaratively configurable through DOM and require no Javascript to use.

## Built-In Table Features

- Click column headers to sort
- Drag-and-Drop columns to reorder
- Edit rows with multi-row Undo
- Row paging, filtering, checkbox selection, and multi-select
- Supports table, single row/article, and flowing grid layouts
- Use of HTML5 `template` for customization (Cells, Rows, Column Headers and Footers)
- 2-way data binding with the outside world
- Separate argument input for metadata, presentation and value calculation in all templates
- Local or remote data: AJAX support from server-side pagination