schema: remove generator_import file used for godep

generator_import.go existed to trick godep to vendoring a main
package. Since moving to glide, this file is no longer needed.

schema/generator_import.go

@@ -1,10 +0,0 @@
-package schema
-
-// This file exists to ensure Godep manages a vendored copy of the
-// `google-api-go-generator` library, used by the 'generate' script.
-// Unfortunately since this is a binary package and hence is not importable, we
-// need to trick godep into managing it by providing an import statement.
-
-// This file is not expected to build.
-
-import _ "google.golang.org/api/google-api-go-generator"