add a spec example for caching the store dir on an S3File
add a spec example for caching the store dir on an S3File

UM-USElab/gradecraft-development,mkoon/gradecraft-development,UM-USElab/gradecraft-development,mkoon/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,mkoon/gradecraft-development