Make .v2 in goa.v2 in Go import paths optional
Make .v2 in goa.v2 in Go import paths optional

goadesign-jp/goa.design,goadesign/goa.design,goadesign/goa.design,goadesign/goa.design,goadesign-jp/goa.design,goadesign-jp/goa.design