Transition to python3

[hellcp]

No description provided.

[hellcp]

It seems attachments aren't actually getting uploaded or pastes with attachments aren't saved. I will have a look at how to fix that later

[hellcp]

os.urandom(32) will not work, since bytes and str will have different len after .encode() and .decode() (and AES requires constant key len dividable by 2^4)

[hellcp]

The flake8 tests will require code refactor to be honest

[Conan-Kudo]

@hellcp There is one test failure:

======================================================================
ERROR: test_paste_attachment (test_views.test_paste.TestPaste)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/postmodern-paste/postmodern-paste/tests/test_views/test_paste.py", line 105, in test_paste_attachment
    self.assertEqual('file contents', resp.get_data())
AttributeError: 'tuple' object has no attribute 'get_data'
----------------------------------------------------------------------

[hellcp]

@hellcp There is one test failure:

Yeah, it's an issue with attachments overall, something's very broken

[Conan-Kudo]

I'm merging this so we have something, we can fix attachments later.