Fixed unkeyed fields in file.go for GoogleAppEngine

[wmetaw]

Hi there.
When I deploy into GooleAppEngine. The following errors occured.

File upload done.
Updating service [default]...failed.
ERROR: (gcloud.app.deploy) Error Response: [9] Deployment contains files that cannot be compiled: Compile failed:
go-app-builder: Failed parsing input (5 errors)
github.com/golang-migrate/migrate/source/file/file.go:85:14: composite struct literal os.PathError with unkeyed fields
github.com/golang-migrate/migrate/source/file/file.go:93:14: composite struct literal os.PathError with unkeyed fields
github.com/golang-migrate/migrate/source/file/file.go:101:14: composite struct literal os.PathError with unkeyed fields
github.com/golang-migrate/migrate/source/file/file.go:115:19: composite struct literal os.PathError with unkeyed fields
github.com/golang-migrate/migrate/source/file/file.go:126:19: composite struct literal os.PathError with unkeyed fields

Can you please merge this?

Thank you.

[dhui]

Thanks for fixing. You'll need to use the master branch for now until the broken builds have been fixed and I can cut a new release