Python 3 support

[moggers87]

Fixes #7

• Try to avoid easy_install
• Remove win32 "support" - it was untested and couldn't be used in
  production anyway.
• Mock chardet rather than the string object
• Don't use reserved words
• Do binary file reading properly
• SMTPD messages are slightly different between Python 2 and 3
• Put test states.db in a folder that gets cleaned between test runs
• Depending on what version of Python we're using, reload could in one
  of three places.
• Use more modern try: except: syntax
• Print is a function in Python 3

[moggers87]

There's one failing test, and then I'm ready to merge this, even if Python 3 support is only "experimental"

[codecov-io]

Codecov Report

Merging #53 into master will increase coverage by 0.03%.
The diff coverage is 92.74%.

@@            Coverage Diff             @@
##           master      #53      +/-   ##
==========================================
+ Coverage   93.66%   93.69%   +0.03%     
==========================================
  Files          14       14              
  Lines        1484     1539      +55     
==========================================
+ Hits         1390     1442      +52     
- Misses         94       97       +3

Impacted Files	Coverage Δ
salmon/handlers/queue.py	88.63% <ø> (+0.13%)	⬆️
salmon/bounce.py	100% <100%> (ø)	⬆️
salmon/routing.py	98.68% <100%> (+0.02%)	⬆️
salmon/view.py	100% <100%> (ø)	⬆️
salmon/mail.py	99.35% <100%> (+0.03%)	⬆️
salmon/confirm.py	96.77% <100%> (+0.05%)	⬆️
salmon/utils.py	90.27% <66.66%> (+0.13%)	⬆️
salmon/server.py	91.12% <71.42%> (-1.43%)	⬇️
salmon/commands.py	92.05% <90.32%> (+0.06%)	⬆️
salmon/encoding.py	95.29% <98.18%> (+0.38%)	⬆️
... and 3 more

---

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[astrojuanlu]

Hi! Do you need help to finish this up?

[moggers87]

It needs testing with a proper app before merging. I don't trust the unit tests quite enough to go ahead and merge these changes.

[moggers87]

As I suspected:

2017-11-03 21:00:22,929 - root - DEBUG - Message received from Peer: ('127.0.0.1', 49112), From: b'me@example.com', to To b'you@example.com'.
2017-11-03 21:00:22,929 - root - ERROR - Exception while processing message from Peer: ('127.0.0.1', 49112), From: b'me@example.com', to To b'you@example.com'.
Traceback (most recent call last):                                  
  File "/home/moggers/workspace/inboxen/salmon/py3-env/lib/python3.6/site-packages/salmon_mail-2.99.99-py3.6.egg/salmon/server.py", line 289, in process_message
    routing.Router.deliver(mail.MailRequest(Peer, From, To, Data))  
  File "/home/moggers/workspace/inboxen/salmon/py3-env/lib/python3.6/site-packages/salmon_mail-2.99.99-py3.6.egg/salmon/mail.py", line 64, in __init__
    self.From = _decode_header_randomness(From).pop()               
  File "/home/moggers/workspace/inboxen/salmon/py3-env/lib/python3.6/site-packages/salmon_mail-2.99.99-py3.6.egg/salmon/mail.py", line 40, in _decode_header_randomness
    raise encoding.EncodingError("Address must be a string or a list not: %r", type(addr))                                              
salmon.encoding.EncodingError: ('Address must be a string or a list not: %r', <class 'bytes'>)                                          
2017-11-03 21:00:22,945 - root - ERROR - Failed to deliver message because of "Error in message ('127.0.0.1', 49112):b'me@example.com':b'you@example.com', look in logs.", put it in undeliverable queue with key '1509742822.M930561P1093Q1.youngteazer'