split release job into binaries/docker image

Merge pull request jpillora#246 from pbstriker38/multi_architecture_i…

…mage_build

Multi architecture image build

display client ip in verbose server logs (closes jpillora#233)

go dropped support for mips64p32, ppc, s390

support android retries

IPv6 remotes support (closes jpillora#197, thanks @shawnhwei)

* Support IPv6 remotes

* Adjust validation for IPv6 remotes

* IPv6 refactoring

* Further loosen remote part matching regex

fix Server.Start error (closes jpillora#195)

merge client stdio support (closes jpillora#166 thanks @BoleynSu!)

minor doc changes, test docker build

doc changes, fixed docker auto-build, moved licence to standalone file