Prevent bug in 0.9 upgrade tool

Could have resulted in failures moving old files to new directory.
Document why we do not use fetch in Config initializer
Group related config tools together.

And remove more stubbing in tests.
Rename artifact file methods
More use of Pathname helper
Move helper class
More use of Pathname
Add helper that collects config prep
Add constructor which removes stub_chain
Extract helper for checksumming a file

Makes it slightly easier to read a complicated method.