klepto.archives.db_archive abstracte for PEP249-compliant databases;
moved dill_test* to test_*; added tests for when classdef changes;
fix: added None as second arg for _dict_as_dictproxy pops


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/pathos/klepto@546 8bfda07e-5b16-0410-ab1d-fd04ec2748df
Merge branch 'master' of https://github.com/uqfoundation/klepto