Add Golang 1.11 module files - also resolves 99designs keyring problems on Mac

[beiriannydd]

Fixes this dependency and also as a bonus makes go build work nicely, Mac or Linux (with 1.11)

../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:39:11: undefined: keychain.NewItem
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:40:20: undefined: keychain.SecClassGenericPassword
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:43:22: undefined: keychain.MatchLimitOne
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:49:28: undefined: keychain.NewWithPath
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:53:18: undefined: keychain.QueryItem
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:54:12: undefined: keychain.ErrorItemNotFound
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:76:9: undefined: keychain.Keychain
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:87:12: undefined: keychain.NewItem
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:88:21: undefined: keychain.SecClassGenericPassword
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:199:36: undefined: keychain.Keychain
../../go/pkg/mod/github.com/99designs/keyring@v0.0.0-20180523072454-ccd0779e6f10/keychain.go:88:21: too many errors

[nickatsegment]

Thanks for your contribution, @beiriannydd! We recently did a similar thing for one of our other OSS projects segmentio/chamber#144 and this is a great first step. As written, this won't affect the official builds pipeline. I'll cut an issue to get that on the radar.