Add hibernate support for websockets.
Add hibernate support for websockets.

Return {ok, Req, State, hibernate}
or {reply, Data, Req, State, hibernate} to hibernate the websocket
process and save up memory and CPU. You should hibernate processes
that will receive few messages. So probably most of them.

piboye/cowboy,turtleDeng/cowboy,CrankWheel/cowboy,bsmr-erlang/cowboy,lpgauth/cowboy,cad627/cowboy,noname007/cowboy,acrispin/cowboy,essen/cowboy,yangchengjian/cowboy,binarin/cowboy,unisontech/cowboy,Reimerei/cowboy,binarin/cowboy,MSch/cowboy,odo/cowboy,LineMetrics/cowboy,rbalint/pkg-erlang-cowboy,sile/cowboy,lpgauth/cowboy,linearregression/cowboyku,LineMetrics/cowboy,piboye/cowboy,dangjun625/cowboy,ninenines/cowboy,rabbitmq/cowboy,276361270/cowboy,heroku/cowboy,grahamrhay/cowboy,bobos/ecweb,heroku/cowboy,imdeps/cowboy,nviennot/cowboy,venkateshreddy/cowboy,pap/cowboy,yangchengjian/cowboy,manastech/cowboy,layerhq/cowboy,essen/cowboy,callsign-core/cowboy_hybi00,K2InformaticsGmbH/cowboy,heroku/cowboyku,ferd/cowboyku,unisontech/cowboy,cad627/cowboy,hairyhum/cowboy,layerhq/cowboy,LineMetrics/cowboy,paulperegud/cowboy,omusico/cowboy,manastech/cowboy,callsign-core/cowboy_hybi00,kivra/cowboy,chef/cowboy