[ADD] print, print_docsaway, print_sale : module to print and send docum...

...ents by post, implementation for docsaway webservices.

Print and send documents by post
print : provider base module to print account.invoice
print_sale : print and send sale.order
print_docsaway : implementation of docsAway Provider
myrecordset.filtered(lambda self: self.state == 'sent').mapped('res_id') can't do the trick in a more 8ish style ?