Overriding pattern HTML previews

This idea just came to me and it may be a terrible one.

But if our `patternSource` helper included some bit of data (`isSource: true`) or whatever, we could theoretically do this with our patterns:

``` hbs

{{#if isSource}}

{{else}}

{{/if}}

Some
Really
Verbose
Content
That
Seems
Redundant
To
Show
In
Its
Entirety

```

Not high priority, just something to think about! ¯\_(ツ)_/¯