Does not use model-specific adapters for buildURL

[cristinawithout]

As described at http://emberjs.com/guides/models/customizing-adapters/, each model can have its own adapter where you can customize the method pathForType.

Ember Data Factory Guy uses the default adapter during buildURL, so customizations in model-specific adapters in the pathForType method are not used when building the stub endpoint URL.

This may also be what's happening in #29, but I'm not certain of that so creating separate issue. Pull request to follow.