This patch adds the fetch-mock library, demonstrating how it may be
used to properly mock out API calls. An important change that was
made was the way that 'isomorphic-fetch' was included. Since
fetch-mock makes the assumption that only the window.fetch object
should be overridden, we cannot invoke it via a variable. Instead,
I've simply imported the library, which during import will override
global.fetch if necessary.
Change-Id: Ibd88b61595b4492f375294a8a08031a1a001a10c
4e9cf48b43