browser2: Browser load urls, post, track state

With working tests!
browser2: Add a default timeout

Because no timeout is pretty dangerous
browser2: Handle server issues of postbin.org

And move tests outside.
browser2: Add support for relative URLs / BASEURL
browser2: Better tests

Allow using local services, add RequestBin support.
Still using PostBin for the empty POST issue.
browser2: Better redirection fix

We have to redo request building for all redirection codes even if we
don't fix them, for consistency.
And only 302 seems to be problematic.
browser2: Try to have extensive documentation
browser2: More tests
browser2: Handle Referrer, more documentation
browser2: Import package "cookies"

I certainly don't like doing this, but:
* It is the only cookie lib that does not completely suck.
* It handles multiple cookies in a line, parses flags correctly.
* Clean API
* "One file, so you can just drop cookies.py into your project if you like"
* MIT license

Despite being the best cookie lib available, it isn't well-packaged.

And since for now some light monkeypatching is done, it is even more
interesting to import it.

http://pypi.python.org/pypi/cookies
browser2: Add CookieJar and related cookie handling

Not used by Browser for now, but with very detailed tests.
Does not handle expirations yet.
browser2: PostBin is now disabled

But RequestBin can't help test the bug.
browser2: Handle cookie expiration, session cookies

Every related method accepts a "now" parameter. If provided, it will be
used instead of the system time.
browser2: Evolve _fix_redirect for latest python-requests

See commits:
e831947be43bc97b39d6e6e573cb0842b67fea80
dacc1d8aafedf80f8736d794005b6c8e8b1d4ad1
b20d171c1c11ecee83b7e4a0beead1e54902d37b

The entire redirect thingy will have to be overriden anyway, as it is
still broken. Cookies are given domain to domain without any checks.
browser2: Handle redirects internally

python-requests isn't secure enough, and some behavior depends on the
latest version.
Tested on 0.10.6.

So instead of the previous hack, we have some copy-paste.
But we gain secure cookies handling (not there yet),
referrer handling, "proper" redirect on POST behavior.
browser2: Handle cookies in the request/response cycle

Unlike the one by python-requests, it is secure, and generally behaves
like a real browser.
Basic test added.
browser2: Test cookie override
browser2: Misc doc/refactor
browser2: Add easy cookie building
browser2: Fix cookie security in redirections

With tests (another reason why it's good to write them).