Retain ownership on resized whisper files

This adds a retainOwnership flag to whisper-resize.py so that the newly created files retain the uid and gid settings of the original database files. 
Not a fan of bare except like this. It swallows `SystemExit`, `KeyboardInterrupt`, and is just sloppy python. I like this patch, but please catch the specific exceptions. You should be able to catch both of those with [EnvironmentError](https://docs.python.org/2/library/exceptions.html#exceptions.EnvironmentError)