Adds test for Issue #69

I think this is sufficient to test for Issue #69: creates a test model from the `common.js` description with no properties defined, then the `beforeCreate` hook initializes the `name` property. I tested with Postgres:

~~~
$ ORM_PROTOCOL=postgres node test/run                                
[i] Testing postgres
[i] URI: postgres://markroberts@localhost/node-orm2-test
[0:00:19 0 78/78 100.0% node test/integration/test-validators.js]
~~~