[TIMOB-10291] TiAPI: Transition all event names to lower case designs.

In the aug 1 architectural meeting, it was resolved that events should use only lowercase letters 'a'-'z', for reasons of consistency, aligning with W3C and for making life easy for Alloy. For example: * android:back should be androidback * durationAvailable should be durationavailable To transition, lowercase versions of the events should be made, deprecating but still using the camelCase and namespaced events. Document as such. Then eventually drop the non-lowercase events.