Removing a sale status: STATUS_PAID and Reorganizing sale_status

We are removing sale status PAID, Adding a new column on Sale: paid
to indicates sales that is completely paid.
We are also changing Sale status number to be recognized easily on database:
  1-> STATUS_QUOTE -> enumerated as 'quote'
  2-> STATUS_ORDERED -> enumerated as 'ordered'
  3-> STATUS_CONFIRMED -> enumerated as 'confirmed'
  4-> STATUS_CANCEL -> enumerated as 'cancel'
  5-> STATUS_RETURNED -> enumerated as 'returned'
  6-> STATUS_RENEGOTIATED -> enumerated as 'renegotiated'

Change-Id: Ie96f47ea9d21a45602d053d41cf16b0a6867f7a1