connecion.ConnectionPool.session: Update docstring.

[ci skip]
connection.ConnectionPool: Fix race condition in clean/check_in/check_out

Closes chfoo/wpull#179
http.stream: Handle case where HTTP header is missing.

Closes chfoo/wpull#181
http.stream: Bound max size of headers to 32 KB.
fixup! http.stream: Bound max size of headers to 32 KB.

[ci skip]
connection: Comment out host pool count assert.

re: chfoo/wpull#182
string: Normalize codec name before check for ASCII.

Closes chfoo/wpull#184
Move list of dependencies from readme to docs for conciseness.

Clarify supported platform and Python versions.

[ci skip]
requirements.txt: Pin trollius to 1.0.2 dev on bitbucket.
changelog: Put 0.1000 release date.
sys.setdlopenflags doesn't exist on PyPy, so catch AttributeError
fuzz_fusil: Catch socket.error

re: https://bitbucket.org/haypo/fusil/issue/3/serverclientclose-raises-errno-107

[ci skip]
Add assert messages to some assert statements.
dns: Use repr() instead of coerce_str_to_ascii()
document: Remove to_str() used for Python 2.
factory: Raise error if new() is called more than once per class
connection.py: Assert port is int.
WIP proxy support

re: chfoo/wpull#41

[ci skip]
Move document module into package.
Move scraper module into package.