Add new user fields: creator, date created, and last connection.

This branch also adds a factory object to aid test fixture setup.
Currently it only adds users, but we should add more later.

The container test Factory attributes were renamed to
ContainerFactory so they didn't clash with the Factory attributes
that were added to the base test suite.

Sorry about the size, still working out this git workflow thing.
What about a MakeAnyUser() convenience function which does this?