Initial draft of enginized/gemified app generator

Restructures the code into an engine (/core) and suite of gems (answers
and answers-core).  This also marks the first draft of the new app
generator.  There is still a good amount of work left to restore much
of the original functionality of the rails app (e.g. admin panel,
assets pipeline, gem dependencies, tests, and chef/vagrant bits).

To test, run `./bin/answers MyAnswers` from the root of this project.
Namespace assets and remove unused items.
Correct message to reflect answers mounted at '/'
Namespace views and removed unused files.
Insert answers-core css/js into app's asset pipeline
Namespace controllers. Remove unused items.

Note this setup will use the layout within the engine, not the host app
since the controllers inherit from Answers::ApplicationController.
Mount at '/'. Include minimal gemset in generated app.
Move example and readme files to root.
Remove unused files from answers and refinery template.
Merge pull request #247 from 18F/fix/244_restore-assets-and-views

Restore assets and views in new engine