add Object#to_a if response is not Array.

add Object#to_a method for Rack App's response if the given response
is not Array instance (ex: Rack::Response).
fix
Merge branch 'master' into develop
Support HTTP/1.1 keep-alive

add support HTTP/1.1 keep-alive
 * keep-alive
 * Transfer-Encoding: chunked
 * http pipelining
 * Expect
add reason phrase to status_code