check for errno.WSA* on 64-bit Windows (fixes #1052)

As suggested by Ben, I added `errno.WSA*` versions of various errors to `_ERRNO_WOULDBLOCK` and `_ERRNO_CONNRESET`. I also introduced a new tuple `_ERRNO_INPROGRESS` for the INPROGRESS check, and changed the test suite accordingly. 

The test suite now runs on 64-bit Windows (Python 2.7, Visual Studio 2012), with two exceptions:
```
======================================================================
ERROR: test_request_timeout (tornado.test.simple_httpclient_test.SimpleHTTPClientTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tornado\testing.py", line 118, in __call__
    result = self.orig_method()
  File "tornado\test\simple_httpclient_test.py", line 243, in test_request_timeout
    self.triggers.popleft()()
IndexError: pop from an empty deque
======================================================================
ERROR: test_request_timeout (tornado.test.simple_httpclient_test.SimpleHTTPSClientTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tornado\testing.py", line 118, in __call__
    result = self.orig_method()
  File "tornado\test\simple_httpclient_test.py", line 243, in test_request_timeout
    self.triggers.popleft()()
IndexError: pop from an empty deque
```
It seems that these errors are unrelated to the present issue.