- fix reading config from file specified in CCHTTPSERVER_CONFIG
- move modules into a package and make "python -m cchttpserver" work.
- introduce environment variable CCHTTPSERVER_CONFIG which needs to point to a config file
- restrict keys to be alphanumberic and at least 32 chars long
- renamed blockservice to cchttpserver
- implemented persistent CCFileStorage replacing the Dummy Storage
- added per-user recording of set-operations, store.get_user_keys(user), add store.delete_user() command which clears out all blocks stored by a user
- add http DELETE /USER/ command to delete all blocks from a user remotely (requires that USER to be logged in)