Add a generated dummy app

* Generated from running `rails plugin new …`
Install rspec

* Drop test-unit
* Generate spec following instructions from:
http://stackoverflow.com/questions/8507798/rails-3-1-plugin-gem-dummy-te
st-app-rspec
* Create a symlink from the dummy app to the plugin spec directory
* Running Rspec from root will pick up specs from the dummy app as well
Add jasmine for javascript testing

* Run `rails g jasmine:install`
Create simple assets tests using Capybara

* Confirm that images are being served
* Confirm that the javascript is compiled
Provide jQuery through admin gem

* Bundle up to be included in the govuk_admin_template js include
* Bootstrap is dependent on jQuery, it’s necessary
* Remove dummy app dependencies on jQuery
Shape dummy app to be a minimal admin app

* Include admin styles and js
* Render the admin template
* Use a simple welcome controller and template
* Provide tests for what should be passed to an app’s layout
Add asset test for IE shims
Ignore dummy app logs
Proxy jasmine rake calls through to dummy app

Running jasmine from root prevents the spec files from being compiled
through the asset pipeline. The way the jasmine gem works doesn’t play
well with engines, it uses a lot of non-public APIs.

By proxying the rake task through to the dummy app we fool jasmine into
thinking it’s testing a full rails app, and we get the test and test
results we need.
Delete unnecessary parts of the dummy app
Stub a jasmine spec

* Prove that the specs are using compiled assets as expected
Delete db requirements from dummy application

* Reduce noise and simplify dummy application
* Followed instructions from
http://stackoverflow.com/questions/3954307/rails-3-how-do-i-avoid-databa
se-altogether
Import dummy rake tasks

* Running bundle from within a rake task caused the jasmine:ci task to
fail unexpectedly
* Loading the dummy_app tasks within a namespace and calling the
jasmine tests through that works as expected
Add RSpec spec task
Pin the Ruby version for development

It doesn't affect any users of the gem itself, but it makes working on the gem
more predictable.
Remove unneeded dependencies in Gemfile

They're already in the gemspec.
Fix unresolvable development dependency tree

The number of combinations of dependencies was so large that Bundler was taking
a very long time (forever?) to resolve the dependencies. Pinning the dev
dependencies doesn't affect users of the gem.

Also require Rails 3.2 and above - not strictly required in this change, but
all of our apps are on 3.2 and above anyway.
Create default task to run tests
Include javascript in template

* Don’t require applications to put javascript in application.js, setup
beforehand
* Leads to one more HTTP request on first hit, but subsequent cache
benefits afterwards
Hyphenate javascript filename

* Be consistent in naming patterns, both internally and with other
apps/gems
* Hyphens are common practice in HTML