Include the legacy pouch.d.ts in the new repo as a versioned d.ts

[AGBrown]

Each api version change theoretically needs a versioned file published (and maintained) for it as per the DefinitelyTyped contribution guide. We do not want to discard the old pouch.d.ts file when we contribute to DefinitelyTyped, so we should include it as pouchdb.d.ts-0.1.0.d.ts.

However, this therefore needs a review of the license/copyright (see #8) in this repo before we can pull that file in (which is currently set to the quick and dirty defaults I put in place to get this thing off the ground on a saturday afternoon).