Changes to embed the GMSMapView in a sub-view of the main screen.

Updated to embed the GMSMapView in a view on the main screen named mapView.
This should allow the storyboard to be worked on independently from the
underlying code for the map presentation.
Renamed the ViewController object to MapViewController

Made sure that it was a 'git mv' rather than letting Xcode delete the
ViewController.{m,h} and create MapViewController.{m,h}, which would have
obscured the revision history...  This is just so that as the story board gets
filled out with other scenes, the UIViewControllers that they correspond to can
be filled in and have names that reflect what they do.
Transitioning to Brandt's database
Added the rough-in code for placing the POI markers.

This doesn't use icons for the markers, nor does it do the custom info bubbles
to handle the URL click.  But it does get them on the screen with pop-ups for
the POI name.