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