Fixed up event doc structure (closes #14, #15, #17, #21)

(really sorry about the massive commit ... spec will settle soon)

Still not quite "Alpha" - but getting close! :)

* moved sections around, make the document more developer focused.
* defined flags to keep lock state
* defined the `WakeLockEvent`
* specified how event is fired
* onlockchanged  is now onlost
* fixed up dependencies section (and moved it to bottom of doc!)
Merge pull request #27 from w3c/event

Fixed up event doc structure (closes #14, #15, #17, #21)