#50 No dup checking on xdoclet config

[Michael Nash]

If you define two models with the same name via XDoclet
attributes (e.g. two different Model classes with the same
@x-avalon.info name=xxx entry), bad things happen.

Specifically, the container will get one of them with no
complaint, but it appears entire random *which* one.

We should have some kind of rudimentary duplicate checking
here.