Adding a script to generated _index.html files directly on Google Storage for
Developers. While less ideal than using a live generated index, this allows the
sandbox.google.com/storage interface to be used to authenticate ACL controlled
access to particular paths/buckets.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/2838033

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/gsd_generate_index@51169 0039d316-1c4b-4281-b951-d872f2087c98