Abort RSpec runs on first failure

* Add config.fail_fast = true to spec_helper.
* Move generators config out of RSpec config method.
Upgrade to Rails 4

* Manually create .gitkeep directories. The
  `empty_directory_with_gitkeep` method is removed in Railties 4.
* Remove custom strong_parameters gem. Rails 4 includes it by default.
* Fix syntax. Syntastic reported an issue with some regular expressions.
Use New Relic RPM gem >= 3.5.7 for Heroku accuracy

http://blog.newrelic.com/2013/02/21/using-new-relic-on-heroku-read-how-our-new-ruby-agent-measures-queue-time/
Update Rails version in README.md
Test factory only if it responds to valid?

Allow Factory Girl to be used for non-ActiveRecord objects:

    FactoryGirl.define do
      factory :bundle, class: Hash do
        initialize_with do
          { test: :fail }
        end
      end
    end
Generators don't generate request or routing specs

These specs are better written manually as-needed or tested implictly
via other specs.
Add missing newlines to end of files

This causes GitHub to show a warning in the diff. A newline is added by
default when using Vim, so the file would be changed by simply opening
the file and saving. Neither are ideal.

Hat tip @salbertson
Remove jQuery UI

Only 40% of our recent projects have been including jQuery UI.

The intention of Suspenders is that we're including dependencies only if
we find ourselves using it on just about every thoughtbot project.
Serve static assets, log to STDOUT in staging/prod

The rails_12factor gem currently does two things in staging and
production environments:

* config.serve_static_assets = true
* Logger.new(STDOUT)

Rather than manage the intricacies of how these settings will change in
future versions of Rails, we should rely on the gem.

https://devcenter.heroku.com/articles/rails-integration-gems
https://github.com/heroku/rails_12factor
https://github.com/heroku/rails_serve_static_assets
https://github.com/heroku/rails_stdout_logging
Bump to 1.4.0
Make it easier to find the license

http://docs.rubygems.org/read/chapter/20#license
Add Neat

* Set up Neat in `application.css.scss`.
* Remove empty `_screen.scss` file.
Update README with more complete list of gems
Remove .DS_Store files
Remove `assets` group from Gemfile

Rails 4 removes this group so we can remove it and include the gems that
were in it for all groups. In Rails 4 the production environment will
not try to dynamically generate any assets by default and use the static
precompiled assets and to go along with this change the assets are now
intended to be precompiled in the production environment.

If you're running rake assets:compile to precompile the assets you'll
need to set the environment to production first.

    RAILS_ENV=production bundle exec rake assets:precompile

http://railscasts.com/episodes/415-upgrading-to-rails-4?view=asciicast
Replace Bourne with RSpec Mocks

We explicitly request RSpec Rails >= 2.14 in order to get the stubbing
and spying features of RSpec Mocks:

https://github.com/rspec/rspec-mocks/commit/e8cae54c46f20128ec16c4355f5898c48a8d2d91

We don't need to include the `rspec-mocks` gem directly in the `Gemfile`
or directly configure it in `spec/spec_helper.rb` because `rspec-rails`
includes it as a dependency and defaults the `mock_with` configuration
to it.

Benefits:

* Officially supported by RSpec team.
* Compact.
* Good failure messages.
Replace Sham Rack with WebMock

* Use WebMock to disable HTTP requests to external services in the test
  suite.
* Move `spec/spec_helper.rb` logic to its own template to improve
  readability.

WebMock has broader community support, is well-maintained, and works
with a variety of HTTP libraries.

https://github.com/bblimke/webmock
Force `bundle install` instead of Travis default

Travis CI runs `bundle install --deployment` by default and will install
the gems into `vendor/bundle`, thus making `bundler` gem unavailable
during the tests.
Remove old Rails 3 asset precompilation

Now unnecessary in Rails 4.

https://devcenter.heroku.com/articles/rails-asset-pipeline#troubleshooting
Update .gitignore and .keep files

* These directories already exist and have a `.keep` file.
* Follow Rails' convention of `.keep` instead of `.gitkeep`.
* Totally replace `.gitignore` for cleanliness and to allow Suspenders
  to be run with thor's `-G` flag.

Fixes:

https://github.com/thoughtbot/suspenders/issues/183