Fix to npm run build error and fire-migrate not found error

[19007361]

Resolves issues #32 and #25 Typescript needed to be updated along with the @types/node README updated to make it clear that npm run build-link will find fire-migrate (and also, let's put fire-migrate in the command description itself.

I have a lot of appreciation for this code, it is incredibly useful.

[rayfarer]

The project would not build until I pulled these changes in. Now it works like a charm.

Can confirm this worked perfectly on the first try. Thank you so much.