Remove node().implement, make it a part of node() instead

[Max Stoiber]

Instead of

node(…).implement({
…
})

Combine it with #3 and make it:

node({
…
…
})

[Jovi De Croock]

Should be resolved by this commit any opinions here?

I also changed the datasource by adding in __typename so that isTypeOf isn't needed until they explicitly start using the interface type in a query-field.

[Max Stoiber]

Amazing!!