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
Restores Devise and ActiveAdmin in Answers::Engine

Mounts active admin in generated app
Adds to migrations for Devise and ActiveAdmin
Adds questions and tags to Active Admin dashboard
Humanize names of models in ActiveAdmin dashboard
Merge pull request #256 from 18F/fix/243_restores_admin_sync

Restores Devise and ActiveAdmin in Answers::Engine
Monkey patch Engine to copy migrations to host app

This monkey patches the rails Engine to copy the engine's
(answers-core) migration files to the host app as per:
http://pivotallabs.com/leave-your-migrations-in-your-rails-engines/
Include AATO after answers to set migration order

This causes AATO to be loaded (and its migrations) after answers-core.
It also moves all dependecies after answer-core and any other answers-*
plugins.
Remove debugging statements and unused generators
Merge pull request #250 from 18F/fix/249_copy-db-migrations-to-host-app

Copy DB migrations to host app and correctly set order.
Restoring API controllers and routes.

- adds the `Answers` namespace to API controllers
- adds RESTful routes in config/routes.rb to expose these controllers
- fixes a few small errors in the Tag and Tagging API controllers
Merge pull request #253 from 18F/fix/248_restore-api

Restoring API controllers and routes.