veyron/tools/playground: Fix shell test import paths.
veyron/tools/playground: Fix shell test import paths.

Change-Id: Id9f370c2150694f5659fc73784bba2cc8a309b21

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref