[fix] default view options should be {} and not undefined

Reported here https://github.com/marionettejs/backbone.marionette/pull/752
Introduced here https://github.com/marionettejs/backbone.marionette/commit/f3c632dd
Merge pull request #762 from marionettejs/sjs/fix-default-view-options

[fix] default view options should be {} and not undefined