Add 'finalize' and 'import_path' to Allocation

This is not to be merged yet but I am seeking code review.  Some pre-code discussion has already occurred.  In case you are interested it was [nnutter/gms-core #1](https://github.com/nnutter/gms-core/pull/1).

I still need to add a timeline event for finalize and there is a bunch of refactoring/cleanup of Genome::Disk::Allocation, Genome::Sys, and Genome::SoftwareResult and some subclasses that can happen once this is in place.
I agree that `import_from` shouldn't delete itself since it didn't create itself.  (Should the delete be moved to `create_from`?)