"Conversion/implementation of "authorizer" code from origin, handling
permissions management for users/resources.
Default implementation keeps mapping of <user.resource>->{permissions}
in a table, contents of which is cached for slightly quicker checks.
Adds access control to all (existing) cql statements.
Adds access management support to the CQL impl. (GRANT/REVOKE/LIST)
Verified manually and with dtest auth_test.py. Note that several of these
still fail due to (unrelated) unimplemented features, like index, types
etc.
Fixes#1138"