Add Python 2.3 support

This commit also adds the 'six' dependency
Don't try to inherit from the real response object
urlencode moved in py3
let's add boto as a supported client, and maybe we dont need the empty travis env anymore
add more tox envs
fix self.closed in python3, and request must inherit from httprequest for httplib2
expose sock, pass correct args to connect in stubs.  should fix httplib2 in python3
need the sock for httplib2, don't want sock for requests, can't we all just get along?
add AWS keys to travis
pep8 cleanup
use six.moves instead of _compat
Update README.md
bump version to v0.7.0
new_episodes has been unable to use

I just found that it has been unable to use, is it?
Merge pull request #68 from smallcode/patch-1

new_episodes record mode has been unable to use
Revert "Merge pull request #68 from smallcode/patch-1"

Never mind, I do seem to have support for this.  I'm not sure
why @smallcode was having issues with it, but I'm going to
beef up the test for it a bit to try to figure out what's broken.

This reverts commit c83134ca39569890e3e0233ce97c47ac40ba754d, reversing
changes made to b7cbd181f461e9e6a0d83c844e50083218dcfe9f.
beef up the new epsisodes test a bit
Add a failing test to illustrate a hole in vcrpy's Boto support

This test will fail with the following error:

TypeError: unbound method __init__() must be called with VCRHTTPConnection
instance as first argument (got CertValidatingHTTPSConnection instance instead)

The TypeError is raised because the __init__ method of Boto's
CertValidatingHTTPSConnection (which extends httplib.HTTPConnection) calls
httplib.HTTPConnection.__init__, and during the test httplib.HTTPConnection
actually refers to the patched verison (i.e., VCRHTTPConnection).  When
VCRHTTPConnection.__init__ is called, it expects to receive a
VCRHTTPConnection object as its first argument, but instead it receives a
CertValidatingHTTPSConnection object.  Because the only ancestor class of
CertValidatingHTTPSConnection is the original, un-patched
httplib.HTTPConnection, the first argument is not considered to be a
VCRHTTPConnection object, so a TypeError is raised.
Add full support for Boto

Before this change, vcrpy would not work with modules of Boto (e.g., boto.iam)
that use Boto's CertValidatingHTTPSConnection to connect to AWS (unless you
went through the extra effort of disabling certificate validation during the
tests).  This change adds support for those modules.
Merge pull request #72 from marusich/master

Add full support for Boto