allow for multiple user identities with access rights to the database

[maney@…]

The current design assumes that only one user identity will be used for all database operations - from creating the database through inits and on to access from mod_python. This makes it very difficult to use ident auth (suitable for small, single host setups) and may be an issue even whent hat's not an issue. It's probably not too hard to remove this limitation.

requires

• a setup option to list other user ids to be allowed access
• generate SQL GRANT statement(s) whenever a table is created (sequences too?!)

And I think that's about it, at least for postgres.