No need to manually swap server/client fetchr file.

We use libs/fetcher.js on the server and libs/fetcher.client.js on the client. Which meant that when require('fetchr') was called we had to grab different files based on the environment(server or client).

This is no longer necessary due to the browser key in package.json where we can explicitly substitute the client file for the server file, and allow users to not worry about this minor detail anymore.