add source at the root folder to make CI works

[rande]

As there is no go source at the root folder, integration scripts using

go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v

cannot work properly as go get expect one golang file. See https://github.com/rande/gonode/blob/master/Makefile and the related travis-ci fealure for reference: https://travis-ci.org/rande/gonode/jobs/109252027