Add spring-commands-rspec gem
Add binstubs
Introduce WidgetCreator

I could possible have stubbed out WidgetCreator
as a constant.

I had to add a blank view corresponding to the `create`
action. I suspect this is due to Rails internals always
expecting a controller action to perform either a render
or a redirect. I will investigate this later.

I have disabled 4 specs that no longer apply since
we are moving this responsibility into WidgetCreator.