Add support for coproducts of H functors

[andyscott]

• Adds CopH, a coproduct for types of shape H[_[_]].
• Adds FirstH evidence for summoning shape H[_[_]]
• Adds a basic demo

Additionally there was a discussion on what to name different shapes. I think we'll ultimately follow:

name    shape
 A       T
 K       T[_]
 H       T[_[_]]
 HK      T[_[_], _]

[andyscott]

Scalaz build is broken. I'll fix it this weekend.

[raulraja]

👏