Be explicit that without -r you need to set GOPATH
Be explicit that without -r you need to set GOPATH

I just joined a team that believed they were using `godep`... except we
don't use `-r` and none of our build scripts used `godep go` or `godep
path`.  I realize it's kind of documented already, but I wanted to add a
really explicit statement that you have to do one of these things or
else you will silently end up with non-reproducible builds.

ncdc/godep,mapix/godep,snowsnail/godep,kinvolk/godep,ReachingOut/godep,AndBicScadMedia/godep,njohns-grovo/godep,michaeltrobinson/godep,takecy/godep,jonboulle/godep,buddhamagnet/godep,msn217/godep,thorning/godep,SDkie/godep,beni55/godep,vincentcr/godep,triggit/godep-legacy,ofer43211/godep