[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
Maybe simplify the if / else
 - if record.attachment_id: # compute page number
- elif not record.attachment_id and record.res_model and record.res_id and report: # check report
- elif not record.attachment_id and record.res_model and record.res_id and not report: # error 1
- else: # error 2