Complete set of failing tests.
SortableMixin doesn't currently work if sortAscending and sortProperties are set at the same time.
Failing tests either copied from or based off of https://github.com/emberjs/ember.js/pull/3422
Invalidate previous sorting if sortProperties changes.
Merge pull request #4722 from nathanhammond/master

[BUGFIX beta] SortableMixin properties can't be set with setProperties.