This change adds a basic bandit config for cloudkitty. It can be invoked
by running the tox environment for bandit;
tox -e bandit
These changes also fix potential security issues find during bandit checks.
- binding to all interface: remove useless host_ip option to avoid issue
- hash function issue: switch from sha1 to sha512
- use of exec: can't be removed for moment so using #nosec comment
Change-Id: Iae7d7604457345fe6d482cf48311c9b75fdde947