u-root install issues with no GOPATH?

[brho]

for whatever reason, i don't have a GOPATH set. i hacked nerf.go to skip the ENV check. not sure if that broke something or not.

2019/02/13 14:54:01 ----------> Start
go get: warning: modules disabled by GO111MODULE=auto in GOPATH/src;
	ignoring go.mod;
	see 'go help modules'
2019/02/13 14:54:03 ----------> Finished Get u-root source

i don't know if this got the right u-root. i happen to have an older u-root on my system, v2.0.0. the go.mod for this repo is v4.0.0+incompatible.