GOPATH adjustments

[ctaggart]

See microsoft/vscode-go#185 (comment)

There are 3 sources for GOPATH:

1. export in ~/.bash_profile such as export GOPATH=~/go
2. environment variable such as GOPATH=pwd code .
3. go.gopath workspace settings .vscode/settings.json

Currently, if 1 is used, it wins even if 2 is used. The problems appears to be that VSCode load is sourcing ~/.bash_profile. If it didn't do that, I think the setting of GOPATH would make sense.