update vsts agent download link

update windows server core version

remove unused line

install powershell

use smaller windows footprint

remove vsts_agentname from environment

update choco command

update copy item sdk command

add name parameter for registering agent

copy dotnet core sdk to msbuild tools

add dotnet 4.6.2

split changes for docker using msbuild only and vs2017

update license

add license

update readme