Cleaned up application.appRegions spec
Fix conflicting API for setting an el`s content.
Remove hard dependency on jQuery.Deferred quirks

jQuery.Deferred objects are not compliant with the Promises/A+ standard.
Replaces Promise#done() (not part of the standard) with Promises#then()

This fixes the jQuery.Deffered dependency discussed in #980.
It also exposes Marionette.Deferred as a means to configure the desired
implementation.

e.g.
```
Backbone.Marionette.Deferred = Q.defer; // kriskowal/q
Backbone.Marionette.Deferred = when.defer; // cujojs/when
```
Thisify region tests
Add regionManager getAll method.

This allows for a user to perform batch actions on
a set of regions on both the application level and on
the region manager level. Allowing someone to act across
a collection of regions.
Remove unused build file