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