Major Refactor of Stubs

So the stubs were getting out of hand, and while trying to add support for the
putrequest and putheader methods, I had an idea for a cleaner way to handle
the stubs using the VCRHTTPConnection more as a proxy object.  So
VCRHTTPConnection and VCRHTTPSConnection no longer inherit from HTTPConnection
and HTTPSConnection.  This allowed me to get rid of quite a bit of
copy-and-pasted stdlib code.
add tests for boto