Add typescript definitions

[moonray]

It would be great to have typescript support.

[moonray]

This is the type definition that I believe should work.

declare module 'apollo-client-mock' {
  import { NormalizedCacheObject } from 'apollo-cache-inmemory';
  import { ApolloClient } from 'apollo-client';
  import { ITypeDefinitions, IMocks } from 'graphql-tools';

  export default function setupClient(
    mockResolvers: IMocks,
    typeDefs: ITypeDefinitions
  ): () => ApolloClient<NormalizedCacheObject>;
}