Added stub for runners section of testing guides
Added docs for using the Karma test runner
Added note about other configuration options available to karma
Added testing guide for testem test runner

TODO: There are a few hyperlinks that need to be filled out... can't do
it from a plane bro
Added info about manually running tests in browser

TODO: This needs some love once I get on the ground and get me some
WIFI.
Added info about test reports and build integration.

TODO: This needs love
Updated links for to other references
Added example of manually running tests in browser
Added docs for generating reports from karma
Added docs for generating reports from testem
Merge pull request #2 from mattjmorrison/testing-redux-karma-runner

Initial docs for using the Karma test runner.