Added System Facts generator method.

When creating a new system via the API, one can also specify system
`facts` so that information about the underlying operating system and
hardware can be processed and displayed by the web ui. Furthermore, this
type of information is used internally by `Candlepin` to determine
whether your `Satellite` system has enough (and the right type of)
subscriptions to make your system fully compliant.
:+1:

I think the word you're looking for is [prototype](https://en.wikipedia.org/wiki/Prototype_pattern).