implement ability to listen on unix domain socket
implement ability to listen on unix domain socket

If server option `host` contains a `/` then it is assumed
to be a unix domain socket and the server will listen on it
rather than TCP.

`server.info.unixDomainSocket` will contain the absolute path
to the socket it is listening on.

toboid/hapi,ryanmurakami/hapi,udhayam/hapi,analytically/hapi,DJMcK/hapi,pandeysoni/hapi,SimonLab/hapi,pandeysoni/hapi,bells17/hapi,rodfernandez/hapi,camerow/hapi,jrmce/hapi,credosam/hapi,wookiehangover/hapi,elnaz/hapi,aulvi/hapi,jefflembeck/hapi,StudyForFun/hapi,youprofit/hapi,HugoRLopes/hapi,Marsup/hapi,Binarytales/hapi,ClaudeHarry/hapi,jefflembeck/hapi,cesarmarinhorj/hapi,ryanmurakami/hapi,shalomabitan/hapi,hulbert/hapi,papimomi/hapi,wzrdtales/hapi,zhoujia123/hapi,papimomi/hapi,danielb2/hapi,evdevgit/hapi,aulvi/hapi,wookiehangover/hapi,rodfernandez/hapi,analytically/hapi,elnaz/hapi,pandeysoni/hapi,elnaz/hapi,DJMcK/hapi,evdevgit/hapi,youprofit/hapi,zhoujia123/hapi,Binarytales/hapi,danielb2/hapi,vertiman/hapi,julianduque/hapi,bbondy/hapi,cesarmarinhorj/hapi,camerow/hapi,deepakshrma/hapi,ldesplat/hapi,Eric013/hapi,Marsup/hapi,HugoRLopes/hapi,deepakshrma/hapi,ldesplat/hapi,julianduque/hapi,hulbert/hapi,jrmce/hapi,rmoorman/hapi,udhayam/hapi,StudyForFun/hapi,ClaudeHarry/hapi,vertiman/hapi,bbondy/hapi,toboid/hapi,Eric013/hapi,SimonLab/hapi,credosam/hapi,rmoorman/hapi,wzrdtales/hapi,bells17/hapi,shalomabitan/hapi