pypy 'incorrectly' raises a plain ssl.SSLError where CPython would raise a ssl.SSLEOFError, even though pypy defines that class. But pypy doesn't try too hard to match exact exceptions with cpython.

Add unit tests for sending empty data using sendall, sendall with a
timeout, and send. Note that SSLSocket.send(b'') *does* raise EOFError,
just like the standard library.

This avoids a printed/ignored KeyError seen on PyPy/arm. [skip ci]

This showed we were missing implementations for socket.sendfile and
get/set_inheritable.

Fix ssl tests under 3.3 by creating the check_hostname attribute. Bump tested 3.4 to 3.4.4 due to test errors seen under 3.4.3.

(Well, actually the version that fixes the svn.python.org certificate
problem, as of https://github.com/python/cpython/commit/e5b4fee762a5f4954912e4cbde0ba113b687a66f.)

This showed several errors in our SSLSocket impleentation:

- read/write/do_handshake raise the correct error for unconnected
  sockets.
- SSLSocket.unwrap returns a working socket object
- SSLSocket allows changing the context
- SNI callbacks get a working SSLSocket that can change the context

Update py27 tests

We have unix newlines in the file, the server returns dos newlines:

======================================================================
  FAIL: test_socketserver (__main__.ThreadedTests)
  Using a SocketServer to create and manage SSL connections.
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "test_ssl.py", line 2436, in test_socketserver
      self.assertEqual(d1, d2)
  AssertionError: '-----BEGIN PRIVATE KEY-----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\nSPIXQuT8RMPDVNQ=\n-----END PRIVATE KEY-----\n-----BEGIN CERTIFICATE-----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\nCRlNBAAlvhKzO7Clpf9l0YKBEfraJByX\n-----END CERTIFICATE-----\n' != '-----BEGIN PRIVATE KEY-----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\r\nSPIXQuT8RMPDVNQ=\r\n-----END PRIVATE KEY-----\r\n-----BEGIN CERTIFICATE-----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\r\nCRlNBAAlvhKzO7Clpf9l0YKBEfraJByX\r\n-----END CERTIFICATE-----\r\n'

Also update the test_ssl.py to cpython rev 2c9ff9e (head). This fixes the
problems with invalid certs for svn.python.org.

These tests include much more testing of the new-in-2.7.9 SSLContext
settings, which revealed some problems in our hostname validation, our
handling of read/write/do_handshake for closed sockets, and the missing
alpn_selected method.

Fix #289. Avoid OverflowError in Py2 for large WSGI uploads.

Note Jason Madden as current maintainer

Clarify documentation for Group.join and Event. Also a TODO comment about Event vs AsyncResult. [skip ci]