Minor Improvements and Bugfixes

* serialize and deserialize functions properly (for the state transfer)
* move the client-side debug option from window.debug to window.swac.debug
* don't save models when their are no data changes
* add grouped collection method #getOrCreate(groupId)
* fix pivot key change handling for sorted grouped collections
* allow absolute paths in done.redirect()
* improve view helper to receive the proper context