Added missing nodemon devDependency.
Added missing nodemon devDependency.

After cloning the project and running `npm install`, `npm run dev` would fail unless you happened to have nodemon installed globally. It is best practice to define dependencies per-project.

apollostack/apollo-client,apollographql/apollo-client,apollographql/apollo-client,cesarsolorzano/apollo-client,apollostack/apollo-client,cesarsolorzano/apollo-client,cesarsolorzano/apollo-client,apollostack/apollo-client