
require 1.8.3 SDK.
blobstore downloader expects content type. Set a default gcs file content type like production gcs. 



Revision created by MOE tool push_codebase.
MOE_MIGRATION=6602


git-svn-id: 3f46d6ac2040cd462fa3667a3400c83a82e084d9@92 d537cd30-a800-f30c-cc8c-eaa9e1c31ce9

Khan/appengine-gcs-client,Khan/appengine-gcs-client,Khan/appengine-gcs-client