3.0 - Event simplification and Helper event migration

This is the first pull request in an upcoming series focused on cleaning up and streamlining the callbacks used in the various tiers of the frameworks. I've made a number of intentional and API breaking changes:

* No more enabled/disabled get/set methods on Collection/Factory objects.
* Many options removed from Event subsystem.
* passParams is always on now, and there is no way to disable it. Fewer configuration options and runtime options means simpler code that requires fewer tests and less documentation. I'll be removing more options/flags in future pull requests.
* Helpers now directly bind to event managers. This cuts out a layer of indirection saving some time.
* Helper no longer implements callback methods. While this breaks callbacks with parent calls, it also greatly reduces the number of event handlers that are bound/invoked cutting response times down.

I've documented the plan I'll be following for the larger set of changes [in this wiki page](https://github.com/markstory/cakephp/wiki/Event-system-cleanup).