Split destination classes out into separate files and finish cleaning up the tests

apps/cli/executables/delivery/delivery/context.py

apps/cli/executables/delivery/delivery/deliverer.py

...li/executables/delivery/delivery/destinations/__init__.py

...li/executables/delivery/delivery/destinations/checksum.py

...i/executables/delivery/delivery/destinations/fetchfile.py

.../executables/delivery/delivery/destinations/interfaces.py

apps/cli/executables/delivery/delivery/destinations/local.py

...i/executables/delivery/delivery/destinations/sharedweb.py

apps/cli/executables/delivery/delivery/destinations/tar.py

apps/cli/executables/delivery/test/test_cli.py