issue #20864: sales order grid entry

This is a fully-baked implementation of grid-entry, which (with QA approval) can be released into production.

The implementation here is a straightforward one and works well, but is likely to strain under the weight of 50+ line items. We have a few speculative options for reimplementing parts of the grid with better support for large sales orders, such as with an enyo list or with cells that are read-only labels until tabbed into.

There's also an open issue with the keyboard navigation of pickers.
http://forums.enyojs.com/discussion/1578/picker-onblur
If enyo pickers cannot be made keyboard-friendly we might want to replace them with comboboxes throughout the entire application.