Fold .httplib_request() directly into .http_request().
Fold .httplib_request() directly into .http_request().

* riak/transports/http.py:
  (RiakHttpTransport.http_request): adjust param names to URI and BODY to
    match the expections of the .httplib_request() method body. fold that
    method into http_request. alter header examinatino to "is None" so we
    don't (unnecessarily) fire on an empty dictionary.
  (RiakHttpTransport.httplib_request): folded into .http_request()
  (RiakHttpReuseTransport.httplib_request): renamed to .http_request()
  (RiakHttpPoolTransport.httplib_request): renamed to .http_request()

basho/riak-python-client,basho/riak-python-client,GabrielNicolasAvellaneda/riak-python-client,GabrielNicolasAvellaneda/riak-python-client,bmess/riak-python-client,basho/riak-python-client,bmess/riak-python-client