Dash Docset Generator

As noted in bitovi/canjs#1539, for continued Dash docs support a Dash .docset generator will be needed.

I think Andrew created the first CanJS docsets. Maybe creating the generator will be a simple feat. @booc0mtaco, I'm not sure how the first set was created? Have you already created a generator?
### Regarding Velocity support

Velocity support is also mentioned in bitovi/canjs#1539. Velocity is a Windows version of Dash that uses the same docsets, but the user-contributed docsets (which is where the CanJS docsets currently show up in Dash for OS X) aren't supported right now. Dash uses the OS X-style folder extensions (a folder with `.docset` extension set on it), which isn't supported on Windows, so Velocity uses a .docset file that appears to be a wrapper/installer that moves the same folders into place, as noted in the original issue.