Add in interface for new invoice.
Add in some changes to how create invoice/memo work.
Add in a bunch of changes to creating a new piece.
More progress on creating new inventory items.
Tie in the angular model into the view.
Add in vendor list to new piece creation.
Add in functionality for adding stones/metal/labor to a new piece.
Add in some UI changes to the create piece flow.
Fix parameter name for validation helper
Merge branch 'interface' into pieces
Serve up stub api from live endpoints
Add vendor to memo
Fix invoice stub for show
Create invoices table
Use a join table for memos/pieces
Add invoice seeds
Serve live invoice data for index and show