Start spike of basic Smokestack implementation.

@jdfrens @jwood @morrisco 

Here is a basic spike for the smokestack implementation.  Haven't tried to run it, I'm sure there are bugs and need to add tests.  If this looks like it is going in the right direction, I'll start adding tests and we can open a separate smokestack-engine for the rails engine side of it.

@jdfrens I threw away the idea of a Smokestack specific DSL in place of 'providers'.  My expectation is that on the unit test side, rather than using a DSL provided by Smokestack, developers will continue to use their normal factory DSL, e.g. `FactoryGirl.create(:user)`.  Instead, the smokestack engine will be configured to use a specific FactoryProvider which very simply wraps the factory implementation they are using and makes the requisite calls to generate the objects.  See `Smokestack::FactoryProviders::FactoryGirl` as a very simple example.