rosie delete: add test battery.

Use rose.fs_util to do mkdirs, delete, etc.
Simplify prompting logic.
Remove previously wrongly added test-battery generated files.
Merge branch 'master' into t-rosie-delete
Merge branch 'master' into t-rosie-delete
Merge branch 'master' into t-rosie-delete
Merge pull request #807 from matthewrmshin/t-rosie-delete

rosie delete: add test battery.