[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
Remove unnecessary spaces here and above (+ I spotted some linting issues, check the whole module for some leftover pep8 issues).