Store creation is too inflexible

[BinaryMuse]

There's no good way to create reusable bits of stores, for example, default methods, action handlers, or initialize methods. See #31 for a good example.

Mixins could certainly do the trick (merge action hashes, call multiple initialize methods, mix in other methods and properties), but I'm not sure if it's the best solution for the problem.

[brigand]

Always better to make the api more flexible than adding features for specific problems :-)

If #31 can be implemented as a mixin or other kind of extension, that's ideal.