cloud/google/gcsutil: new package
cloud/google/gcsutil: new package

Methods that we still need for
camlistore.org/pkg/blobserver/google/cloudstorage because
google.golang.org/cloud/storage does not cover all our needs yet.

Mostly copied from camlistore.org/pkg/googlestorage at rev
9f7e1df32b6df16e2d9f5dd85b911d105e269b0c

Change-Id: I128ccaee23d00341b7114329ff437bf954444e5f

camlistore/go4,bradfitz/go4