feat: add support for rotating jwt keys This allows jwt_secret to have multiple ',' separated secrets. The first/leftmost should be used to sign new JWTs. All of them are used (starting from left/newest) to try to verify a JWT. If the first secret is < 32 chars in length JWTs are disabled. If any of the other secrets are < 32 chars, the configuration code causes the software to exit. This prevents insecure (too short) secrets from being used. Updated doc examples and tests.

# In Python 3 the "anydbm" module was renamed to be "dbm" which is now a
# package containing the various implementations. The "wichdb" module's
# whichdb() function was moved to the new "dbm" module.

try:
    # old school first because <3 had a "dbm" module too...
    import anydbm
    from whichdb import whichdb
except ImportError:
    # python 3+
    import dbm as anydbm
    whichdb = anydbm.whichdb