Provide a way to generate "freestyle" at target route

[grapho]

/freestyle is not always the best route for the style guide to live. I, for instance need it to live in a sub directory due to custom server config. It is simple to move the files after they are created, but maybe there can be an option to provide a terminal prompt to pick where you want the route to be located during install?

[mszoernyi]

It would be nice if the generators check for pod structure as well.

[mszoernyi]

@chrislopresto How would we handle the install path then? Should the addon blueprint still create the files or should the user install in 2 steps

ember install ember-freestyle
ember g ember-freestyle-route custom-route-name