LaunchpadOpenIDStore doesn't support database disconnection

I've put together a branch that implements OpenIDStore in terms of Storm, which removes the problem code paths. The branch does not implement nonce handling because that feature is not required by OpenID providers.

That solves the problem for the SSO server, but leaves the openidconsumer code unfixed. It'd be good to see if we can share as much of the implementation as possible. Here's a sketch of a solution:

1. have a base StormOpenIDStore class that is pretty much the same as my current code, but with the nonce handling filled in.

2. rather than referencing the Storm classes representing associations and nonces directly, go through class variables.

3. provide implementations of the association and nonce Storm classes minus the __storm_table__ attributes.

4. the SSO server and shipit could then subclass the association and nonce classes, filling in __storm_table__ with the correct table names, and make a StormOpenIDStore subclass that points at these two Storm classes.

5. Templatise the current tests in my branch so that they can be run against the SSO and shipit specialised OpenIDStores.

A quickfix is available at lp:~stub/launchpad/openidstore-reconnect-quickfix which handles both consumer and provider Stores.

The StormOpenIDStore implementation is likely the better approach, I suspect it will be less fragile in the long term and I can modify it so the underlying database tables match our coding standards.

I've updated my branch roughly as described above, so it now covers both the provider and consumer stores. The two OpenIDStore implementations share the same set of tests.

Fixed in devel r8461.

The consumer code has also been updated, so this should be fixed for shipit too.