- properly support prepare-msg API and implement get_message_info()

- remove usage of "attr.s" across the code
- make msg.set_file() copy a file into blobdir if it isn't already
- regroup tests
- add set_draft/get_draft API

python/tox.ini

@@ -8,7 +8,7 @@ envlist =
 
 [testenv]
 commands = 
-    pytest -rsXx {posargs:tests}
+    pytest -v -rsXx {posargs:tests}
     python tests/package_wheels.py {toxworkdir}/wheelhouse
 passenv = 
     TRAVIS