fix Expect: 100-continue error

socko can't handle posts from curl version 7.30.0 greater len than 1024 without disabling http 1.1 in the client due to "http 1.1 expect 100-continue" behavior.

to reproduce, post 2k data with curl with and without the -0 "curl -0" option to disable http 1.1.

this fix comes from netty issue https://github.com/netty/netty/issues/2606 resolution