Initial release

@himedlooff Please review when you have a sec. It still needs some work but I think we have a solid foundation. It scaffolds an application similar in structure to [cfgov-refresh](https://github.com/cfpb/cfgov-refresh) and installs selected bower components. I'd like to publish it to npm sooner than later to reserve the `yo cf` namespace.

Still to do:
- Only add Grunt tasks to the gruntfile that are relevant to the components selected by the user.
- Finalize user prompts (currently we ask for things like the user's homepage, not sure if that's necessary).
- Other stuff.
I'll add our info (CFPB, consumerfinance.gov, etc.) as default answers so you can just hit enter when building an internal project. I'd like to leave the prompts there for when it's used by external parties.