Add install generator for Krikri
Use engine_cart and remove dummy app

This replaces the partial dummy app with a full rails app generator and
rake tasks to use it. This makes it possible to test against a full app
more easily, including using different versions of ruby or rails, etc...
Ensure marmottawrapper and jettywrapper tasks work
Merge pull request #3 from dpla/engine-cart

Engine cart