add option to extended start script to replace env vars in config files
add option to extended start script to replace env vars in config files

ingwinlu/relx,Licenser/relx,bitwalker/relx,ethercrow/relx,zugolosian/relx,lrascao/relx,bsmr-erlang/relx,umatomba/relx,RJ/relx,syl20bnr/relx,erlware/relx,tsloughter/relx,priestjim/relx,timclassic/relx