Rob Wormald recognized that we had no plunker for a simple component test. Inspired improved learning path for testing including:
* Add plunkers for both inline and external template versions of the simplest `BannerComponent`
* Added the banner-specs for that purpose and also a quickstart-specs in the setup folder
* Adjusted prose in testing and setup-systemjs-anatomy to call these out
* Moved testing of external template spec earlier in the guide because it is likely to be needed right away.
* Add comments on the optional "testing" folder and corrects var names to match
* Leaves Jasmine Spec Runner output visible when tests finish
