add streaming http client
add streaming http client

sets no timeout, but configures 10 second keepalive

[#86648608]

Signed-off-by: Onsi Fakhouri <462e8268221b0a33cd7976309527393b532710f3@pivotal.io>

cloudfoundry-incubator/cf_http,cloudfoundry-incubator/cf_http