Before this commit the user add to click on vendor bill
button that redirect him to an empty list view where he has
to click on create. Now, vendor bill show a list view of existing
invoice and it exists a new button create bill that directly create
a new invoice with missing delivered product.
It also order button in order to put primary buttons first in the
header.
The tour is modify since the stat button is invisible if the PO does not
have an invoice linked. Instead it clicks on 'create bill' button.
This commit is related to task ID 1835441.
Hetashree Chauhan
4d1d8d457e