PYCBC-114: Internal HTTP wrappers

This provides basic wrappers around lcb's make_http_request, as well as
exposes the administrative handle API. Currently this is not
documented as the API may change.

Change-Id: Ibd084de2b7b56ac0eb09b8c5d62e09cc1e273ecc
Reviewed-on: http://review.couchbase.org/26323
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>