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
Cleaned up collectionView.attachToDOM spec
Bump and build v2.0.0-pre.2
Cleaned up collectionView.reset spec
Cleaned up commands spec
Remove last vestige of Marionette.$ to fix #1406

Running `grep -rn 'Marionette\.\$' .` in the root of the project now
only returns matches in the changelog and the currently existing build
in lib/core.
Cleaned up compositeView.onBeforeRender spec
Cleaned up destroyingViews spec
Merge pull request #1421 from cmaher/fix-1406

Fix 1406
Cleaned up getOption spec
Cleaned up mixinUnderscoreCollection spec
Merge pull request #1424 from thejameskyle/cleanup-destroyingViews

Cleaned up destroyingViews spec
Cleaned up normalizeMethods spec
Cleaned up onDomRefresh spec
Cleaned up precompiledTemplateRendering spec