[enh] #95 remove useless signature argument from Document.__init__

duniterpy/documents/block.py

duniterpy/documents/certification.py

duniterpy/documents/document.py

duniterpy/documents/identity.py

duniterpy/documents/membership.py

duniterpy/documents/peer.py

duniterpy/documents/revocation.py

duniterpy/documents/transaction.py

duniterpy/documents/ws2p/messages.py

examples/save_revoke_document.py

examples/send_certification.py

examples/send_identity.py

examples/send_transaction.py

tests/api/ws2p/test_ws2p.py

tests/documents/test_certification.py

tests/documents/test_transaction.py