Failing specs to show buildRegion is not called for region long form el declaration

Due to `RegionManager`'s current implementations of `addRegion` and `addRegions` ([reference](https://github.com/marionettejs/backbone.marionette/blob/v2.0.2/src/marionette.regionManager.js#L16-L58)), adding regions to `LayoutView` (and `Application`) with the long form declaration suggested in #1530 will not work.  This PR provides failing specs to show a proper region is not built with `Region.buildRegion` if we use the `el` property over `selector`.
What's the benefit of this test with the one above it?