Some queries weren't using the full power of SQL and doing some of
the selection in the code, fix that (by_hash and host mapping).

hide coverage in test code

add tests for migration, good example for future needs..

We were only using the ed448 code, and cryptography requires rust
to compile, and contains a LOT of other code, while edgold is much
smaller, and doesn't require a rust compiler, and will work on more
systems..  Keep around an old identity generated from cryptography
to make sure the two libraries are compatible.

one minor issue is that the identity object gets dump'd twice..

this fleshes out hostuuid better..
add a more useful debug print..

If the identity changed, generate a new uuid, and set created_by and
modified appropriately...

the modified is the correct, not mtime, as someone can put an
"older" modified file, but at a later time, so it's assumed
that the most recently modified fileobject has the most up to
date data..

The later happens after importing a container.

fix up code to pass all the tests...

This was partial work to go to python3, but I've now since learned that
going twisted is not the way I want to work for web frameworks, so a
large amount of this code will be dropped (kleintest.py) or rewritten..

as part of this work, also uplifted automatic promotion of uuid
to a UUID object...

add encode/decode methods to MDBase to make things more simple
when handling serialization...

add new_version that creates a new version with modifications

private members...  also increase coverage back to 100%, delete
outdated comments..

this involved restructing the objectstore to be more of a complete
repo, keeping things like create_by_ref for new objects...