Httplib2

Fixes for App Engine 2.7.

Keys are lowercase in a Response object, regardless of how Response object is constructed.
Add control so that Authorization: headers aren't forwarded on a 3xx response by default.
Set the reason correctly when running on App Engine. Patch from Alain Vongsouvanh. Reviewed in http://codereview.appspot.com/6422051/
Fix proxy socks for SSL connections. Fixes issue 199.
You can now set httplib2.RETRIES to the number of retries before a request
is considered to fail It is set to a default of 2 to mimic the traditional
behavior of httplib2.

The following issues have been addressed:

223 HEAD requests fail calling the close() method of ResponseDict instance.
222 Can't disable cert validation in appengine
204 Credentials can leak in HTTP redirects
210 Different API between Python 2 and Python 3 version breaks wsgi_intercept
214 ValueError on malformated cache entries
204 Credentials can leak in HTTP redirects

ProxyInfo objects now can construct themselves from environment
variables commonly-used in Unix environments. By default, the Http
class will construct a ProxyInfo instance based on these environment
variables. To achieve the previous behavior, where environment
variables are ignored, pass proxy_info=None to Http().

The following issues have been addressed:

Issue 159: automatic detection of proxy configuration.
Issue 179: Allow unicode in proxy hostname.
Issue 194: Added support for setuptools.
Fixes for HTTP CONNECT proxies.

Fix failure to install cacerts.txt for 2.x installs.

The two major changes in this release are SSL Certificate
checking and App Engine support. By default the certificates
of an HTTPS connection are checked, but that can be disabled
via disable_ssl_certificate_validation. The second change
is that on App Engine there is a new connection object
that utilizes the urlfetch capabilities on App Engine, including
setting timeouts and validating certificates.

The following issues have been addressed:

Fixes issue 72. Always lowercase authorization header.
Fix issue 47. Redirects that become a GET should not have a body.
Fixes issue 19. Set Content-location on redirected HEAD requests
Fixes issue 139. Redirect with a GET on 302 regardless of the originating method.
Fixes issue 138. Handle unicode in headers when writing and retrieving cache entries. Who says headers have to be ASCII!
Add certificate validation. Work initially started by Christoph Kern.
Set a version number. Fixes issue 135.
Sync to latest version of socks.py
Add gzip to the user-agent, in case we are making a request to an app engine project: http://code.google.com/appengine/kb/general.html#compression
Uses a custom httplib shim on App Engine to wrap urlfetch, as opposed
Add default support for optimistic concurrency on PATCH requests
Fixes issue 126. IPv6 under various conditions would fail.
Fixes issue 131. Handle socket.timeout's that occur during send.
proxy support: degrade gracefully when socket.socket is unavailable

The following issues have been addressed:

51 - Failure to handle server legitimately closing connection before request body is fully sent
77 - Duplicated caching test
65 - Transform _normalize_headers into a method of Http class
45 - Vary header
73 - All files in Mercurial are executable
81 - Have a useful .hgignore
78 - Add release tags to the Mercurial repository
67 - HEAD requests cause next request to be retried

Mostly bug fixes, the big enhancement is the addition of proper Vary: header
handling. Thanks to Chris Dent for that change.

The other big change is the build process for distributions so that both python2 and python3
are included in the same .tar.gz/.zip file.