Move adapter under config//adapters and let the resolver resolve
adapter.

Removes the need of having window.App defined for specifing an
adapter, now it will be resolved by the resolver. Will also facilitate
things for adding tests with QUnit.
Merge pull request #136 from abuiles/app-adapters

Move default adapter under app/adapters and let resolver resolve the adapter
Mount lib/ into asset load path

Also added engine tests for asset load paths