SPDY: support spdy/3
fix nginx-tfs rcs keepalive bug.

1. fix rc_stat count not initialized bug.
Merge pull request #371 from zhcn381/upstream

fix nginx-tfs rcs keepalive bug.
Merge pull request #369 from chobits/spdy_v3
rollback: undo this commit "test (kqueue)connection completely in ngx_http_upstream_test_connect()"

Undo commit 422086fb7df6daef082fcaf7459b9ce72f84eaf4.

Maxim Dounin's reply for this patch is as following:

On Fri, Aug 16, 2013 at 10:19:00AM +0800, Xiaochen Wang wrote:
> Without this patch, nginx can work well because c->recv() will return
> NGX_ERROR when read event timedout expires.

Note well that the purpose of ngx_http_upstream_test_connect()
call before writing to an upstream is to properly report source of
the error if it happens.  It's bad idea to do getsockopt() in all
cases for performance reasons
Merge pull request #373 from chobits/kqueue_bugfix_rollback

rollback: undo this commit "test (kqueue)connection completely in ngx_ht...
update nginx version
Merge pull request #374 from cfsego/20p

update nginx version
SPDY/3: avoid repeated decrease of recv_window_size if data frame is not received one time

Thanks to Yanmei Li <miaoji.lym@alibaba-inc.com>
Merge pull request #375 from chobits/spdy3_repeated_decrease_rwnd

SPDY/3: avoid repeated decrease of recv_window_size
update testcase
Merge pull request #376 from cfsego/20p

update testcase for limit_req
update changelogs
Merge pull request #377 from cfsego/changelogp

update changelogs
update README
Merge pull request #378 from cfsego/changelogp

update README
SPDY: add SPDY/3 documentation
Merge pull request #379 from chobits/spdy_v3_doc

SPDY: add SPDY/3 documentation